Off the top of my head, New York City, Honolulu, Albuquerque (loved living in Albuquerque) and Santa Fe. Kathmandu. Tokyo and Kyoto. Singapore. Beijing. Luang Prabang (the old royal capital in Laos).
Poipet, Cambodia and Plains, Texas are tied for asshole of the universe.
Loved:
NYC
Istanbul
LA (sorry, guys, but I think it’s a fascinating city and I love driving challenges)
San Antonio (current hometown)
Liked:
Washington DC (speaking of driving challenges!)
Rome (well, this is really between “like” and “love”)
Atlanta GA (Great city to live in, but I can’t understand why the city “fathers” wanted to make it a tourist attraction)
Seattle (had 2 beautiful days there, lovely city and environs)
Dislike:
Athens, Greece (very depressing, though our stay was short. Probably should give it more time.)
Knoxville, TN (personal reasons)
Would consider suicide if I had to move there*:
Bridgeport, CT (possibly the ugliest city I’ve seen in the US)
Buffalo, NY (nice city, but damn I hate the cold!)
Portsmouth, NH (a great place to live if you like the smell of fish)
*Leaving out the standard responses of “East St Louis”, “downtown Detroit”, etc
I’m another Venice hater, picturesque yes, but the entire city just exists to separate the lowest class of stupid lumbering tourist from their money. Literally the only place in Italy you can get bad food. You can see eveything cool from the front door if the train station, so get back on the train and go somewhere better.
Domestically I dislike San Francisco, expensive, dirty, ugly, and the people are sanctimonious dicks. Beautiful area … Once you are out of the city! I’d take Cleveland over SF any day of the week.
London is very eh to me, nothing wrong with it, it’s just too much like NYC (which is where I live) to make an impact on me. I love Florence. It’s been years since I traveled in Eastern Europe so I have no idea what it’s like now but in the 90s I loved Budapest (Hungary) and Plovdiv (Bulgaria)
I think that’s a good way of putting it. You love a city or not partly based on your expectations of it.
I didn’t like New York because it was all too fucking big and confusing. I live in London, btw. I did get robbed in NY, but that was partly due to it being big and confusing. And even less friendly than London. I really liked some aspects of the city and would try it again, but it was not fun.
Paris was a dirty anglophobic hellhole the one time I went there in 1995 or so.
In both of those cities I was expecting something similar to London, but better in some ways and worse in others. NYC was much, much more confusing than London and Paris was much dirtier, and those are things that I’d expected to be similar. My expectations were confounded, and that coloured the whole experience.
Los Angeles I went to becausse friends of mine lived there. Because we were with friends, we saw the good side more. However, I still didn’t even glimpse the nasty things I’d expected about LA when we were out and about on our own.
Washington DC we basically picked because it was on the flight path which made it good place to stop over for four days, but it was much more interesting than my expectations had lead me to believe and it’s on my list of places to revisit.
Naples, Italy, I had always heard was horrible. Natives always told me to avoid it. I didn’t really get why till I went there. God, the squalor right next to the main museum.
Venice is probably lovely if you’re rich. If you’re not, don’t go. The ice-cream is fabulous, though.
If you can love and hate a city at the same time, I’d nominate Ho Chi Minh City (Saigon). It is NOT pretty. Impossible to put any positive spin on that. Apart from some decaying French colonial architecture and boulevards, it is as ugly as a hat full of arseholes. And it’s filthy. However, it is full of energy, vibrant, and awesome. And the food is incredibly good.
Hong Kong is possibly my favourite place, in terms of energy and vibrancy. It has the bonus of also being quite pretty, although it can be dirty and squalid up close. The geography is wonderful.
Love: NYC
Love/hate: London. So many wonderful things to see but dirty, expensive, and people are generally unfriendly.
Hate: I thought Houston was awful.
I love New York. I’m from there, but I love going back. I also love London, and our plans are to live there for six months after I retire, just to see everything.
Love Copenhagen and Stockholm and Berlin. Like Helsinki and Talinn, but need more time there to be sure. Like New Orleans to visit.
Like a good northern Californian, I hate L.A. Not too thrilled about Rome. Cairo is a place I don’t ever want to go back to.
Number one worst city is Kinshasha which was Leopoldville when I lived there 52 years ago. It was awful then, I can just imagine what it is like now.
I love Orlando, Muscat, London, Milwaukee, Mumbai and Tokyo.
I hate Newark, Miami, Frankfurt, Riyadh and Aberdeen.
Love - Zurich
Savannah, Georgia
Zanzibar City, Tanzania (I would walk for days, just looking at the architecture)
Amsterdam
Love and dislike all in one
New Orleans - I tell people I want to find a way to spend 5 days and 1 night in this town.
Dislike - Sparta, Greece (Might have been because of the cold weather, but I found it to, well, spartan)
Dar Es Salaam, Tanzania (Dirty and chaotic, although there are some interesting pockets)
Phoenix, AZ
Most of Florida
I love a bunch of cities:
I don’t really hate any cities, but the ones I found least impressive are:
I’ve been trying to think of cities I dislike just because I found nothing redeeming. Most places I’ve disliked have been because of circumstance and not because the city was crappy. If I had to choose a few:
Geneva, Switzerland: it’s just a boring place full of concrete.
Sofia, Bulgaria: its redeeming feature is that it’s a short drive to Istanbul, which I loved
Los Angeles, for all the usual reasons
Miami, FL: hot, muggy, dirty, buggy
Dallas/Ft. Worth: more and more concrete and Texans
Helsinki: Nice place if you like to drink a lot
Cities I like or love: How much time do you have?
London, Paris, Prague, Copenhagen, Berlin, Vienna, Strasbourg, Marseilles, Brussels, Bruges, Amsterdam, The Hague, Luxembourg, Madrid, Seville, Lisbon, Porto, Rome, Sienna, Florence, Bamako, Kampala, Guatemala City, San Diego, Santa Barbara, New York, Boston, WDC, Anchorage, Portland, Seattle, Tokyo, Misawa, NOLA, and a whole lot more.
20 years in the Navy, over 50 countries. The city which I like the most has not been mentioned yet: Brugges, Belgium. The city center is maintained in a permanent medeival setting. Whenever a building is repaired, it must be done using period methods. Cars are not allowed in the city center, and it has many canals. The canals actually do not stink (I am looking at you, Venice!).
More of my list in no particular order:
Love:
New York (Home!)
Washington DC
Los Angeles(more specifically Santa Monica and Venice Beach)
London
Rome(I could spend a week at the Vatican)
Amsterdam
Glasgow
Reykjavik
Lisbon
Xania, Crete
Sydney
Meh:
Naha
Brussels
Kiel
Gdynia
Brest
Portsmouth, Eng
Plymouth, Eng
Boston
Dover, DE
Hong Kong
Darwin, Australia
Townsville, Australia
Klaipeda, Lithuania
Ventspils, Latvia
Cebu, Phillippines
San Juan, PR
Rota, Spain
Willemstad, Curacao
St. John’s, Newfoundland, Canada
Koper, Slovenia
Dislike:
Dakar
Tokyo
Naples
Naples
Did I say I dislike Naples?
Venice
Sasebo, Japan
Iwakuni, Japan
LOVED
Beijing, China-History, smiles, food, fun. The culture is so wonderfully different.
Istanbul, Turkey-If only more Muslim countries looked to Istanbul for inspiration. It’s cautiously western and just the right balance.
Tallinn, Estonia-A hug straight from a fairy tale.
Jaisalmer, India-The city most haven’t heard about. This oasis near the Pakistani border is something everyone should experience.
Alexandria, Egypt- Even on the Nile, Egypt feels like a dusty place. Alexandria washes this all away.
Rome, Italy-It’s hard not to feel smarter walking around.
Puerto Vallarta, Mexico-Crashing waves, delicious food, liberal feel. This is how Mexico tourism is done right.
HATED
Negril, Jamaica-Really, the whole country’s a shithole.
Amsterdam, Netherlands- I used to like it ok, but the central area is like an overtired frat party. It’s sad what the city has become.
Puquio, Peru-There’s a reason a city this large isn’t in any guide books.
Orlando, FL USA-The stupidest toll roads ever.
Cancun, Mexico-This is how Mexico is done wrong if you’re over the age of 22.
Favourites:
Budapest
Sarajevo
New York
Sydney
Tallinn
Venice (I really don’t understand the hate for Venice, unless everyone on this thread visited in August and followed the mooing herds past the arrows from Santa Lucia to San Marco and back again)
Over-rated (“hate” is too strong a word) :
Berlin
Amsterdam
Prague
Miami
Wellington (actually I’m not sure that it’s even “over-rated” as everyone seems to think it’s dull!)
I’m the homebody in my family. The rest of my family goes everywhere.
My retired parents absolutely adore Prague. They go there at least every other year or more and will be there again in August.
Psst: look at the post before yours. 
I’m not surprised that you didn’t like Rota: it’s a military town without much to redeem it. I like it because of all the places you can get to easily from there. As a Seabee, we had opportunity to travel a bit on our one day off a week. I saw Seville, Grenada, Torremolinos, Ronda, Cordoba, and Malaga, just to name a few.
My honeymoon was in Jamaica, and unfortunately I must agree with the above sentiment. The resorts are nice enough, but you have to drive past mile after mile of squalid shanty towns to get there. You’re advised not to leave the resort unless you’re with a tour group. I really have no desire to ever go back there.
I found Las Vegas to be kinda disappointing. I don’t enjoy gambling, and the glitz was only interesting for about a day & a half. It was more useful as a jumping-off point for a trip to the Hoover Dam (I’d already been to the Grand Canyon). OTOH, I did see the Blue Man Group there, and it was awesome 
I almost moved to Boston, Ma when my then-wife was attending school there.
Almost…good thing, 'cause I hated that place.
I also do not like San Francisco, and not just because they have the Giants there.
I loved Niagra Falls, Seattle, Las Vegas, Santa Fe, Cincinnati, and the entire state of Montana.
Love:
London
Paris
Florence
Venice
Hate:
Copenhagen
Manhattan
Of course, I haven’t been in Venice longer than 36 hours a time, but it’s definitely a place where you need to sit, settle in, and just be. It’s best if you’re staying in the old town overnight. Wait till the tourist hordes leave, then come out and enjoy it.
Hated: Virtually every city in Hawaii, I’ve been to about 40 of them. It’s almost like they know what will make it harder specifically for you and you alone and then make you pay extra for it.
Seoul, S. Korea was a pain to move around in, especially at night. There’s so many people clogging the sidewalks and streets it takes about 30 minutes per block by foot.
Pusan, S. Korea has open sewers, so the entire city smells like doody. In the winter, you can see shit steam rising from them. In both cities, the drinking culture is to keep going until you throw up, so every morning there’s massive pools of vomit up and down every street.
Washington D.C. is essentially a city-sized prison. 3/4 of the city is underground and nearly every room has at least one security guard in it to give you shit about your backpack. When I was there, 2/3 of the National Mall was roped off. On average, I got searched 3 times a day.