What the poll says.
Feel free to add a reason, if you’d like.
For me, it’s January – the longest, coldest, darkest month of the year, no holidays, nothing to look forward to but slogging through it as best I can.
ETA: It just occurred to me that our Antipodean pals are going to throw things off if people are voting based on seasons/weather … oh well …
For me, it’s March. It’s all for personal reasons, rather than reasons like “long” or “rainy”. There’s two birthdays in there that help make it not a pure hell, but otherwise it can go rot.
May, because it’s my month of origin. Plus, May is when I’ve usually managed to shake off the winter doldrums and gotten back into shape.
:smack: Completely misread the question–and missed the edit window to boot. :smack:
Can I change my vote to February, please? 
November, because it triggers bad memories from the past.
January is one of my favorites – who doesn’t love a fresh start? And back to school!
For me it’s March. Miserable weather, and Spring still seems forever away, no holidays (well, St. Patrick’s Day, but IMO SPD, like NYE, would be much improved by being moved to a warmer time of year), and everyone is cranky from a long winter.
No, sorry – I edited the poll question to emphasize “least,” though.
Ok, you March haters – I’m making a list!!!
(There’s a certain important day in March, never a bad month IMHO. And, like me, in like a lion, out like a lamb ;))
Now I hate February even more. 
August. Hot and sticky and no decent holidays.
I wanted to say December, but that would be too cliché
Edit:
Early months reperesent newness, and a fresh set of holiday entitlement from work.
Middle months reperesent summer, and the Isle of Man TT. Edit: And the final payment on my car!
Later months reperesent misery, the dregs of holiday entitlement, decent into winter, approaching stress.
August 8th is Cumberland’s Day (the birthday of George Clifford, 3rd Earl of Cumberland.) It is customary upon this evening to invite a few close friends over for a quiet gathering, then have your girlfriend’s alcoholic madman friend show up with a case of beer and two of his friends and suddenly start smoking a million cigarettes and playing cards and transforming the whole nature of the party, which intimidates your original guests, who then leave, leaving you and your girlfriend and some of her friends who you’re just barely friends with and some loud, burly alcoholics playing cards and smoking cigarettes, drunkenly paw your girlfriend and indelicately suggest a three-way sex encounter involving one of her friends, get yelled at, then in a drunken rage, attempt to plug your ipod into the stereo (replacing the ipod that’s already there) and play “Where Have All The Cowboys Gone” by Paula Cole, and then becoming furious and indignant that the rest of the people at the party don’t share your “nostalgia,” bitterly insist that it’s your house and you get to play whatever music you want, and then drink Manischevitz wine and King Kobra until you black out…then wake up five hours later, stagger to the bathroom, vomit, and go Steak & Shake and eat five pancakes.
September. I hate summer so much, and you think you’ve finally made it and it’s September and thank god. But no. Still hot. Still with the blinding sunshine. September is a tease, a cruel tease.
Heh, I feel that way about April (and occasionally May. Hell, JUNE this last year). I hate the winter, and April is marketed as the end of winter, but… no. Not even close, most of the time.
August in So. Cal. is hot as F***. Hate it.
March in Indiana is a cruel joke of a month. Four weeks of gray and brown slush everywhere, gray skies and freezing weather - the whole state looks like The Road with Viggo Mortensen, and you have to listen to everyone talk about March Madness which is annoying as hell if you haven’t given a shit about IU basketball since the days of Bob Knight. Pretty much the only good thing about March this year is going to be Passover, which, if you’re a completely secular Jew, means a lot of wine, matzo ball soup and rich Jewish food (if you’re an observant Jew, it involves a lot of boring prayers and rituals.) But even Passover doesn’t come until March 29th. The good thing is that this March, I will be in the UK, drinking at pubs and eating deep-fried haggis with curry sauce at 4 AM and seeing a lot of old castles and art and armour. So fuck you, Indiana March!
April is my least favorite.
Weather-wise, it claims to be spring but in reality that usually ends up being just a tease.
At work, April is the month when I have the most crappy, annoying, unceasing workload and with no tangible pay-off, either. I have other busy times of the year, but with those it’s like hard work combined with evidence of a good accomplishment so that I can at least feel good about it, like “Yay, self! You did an awesome job!” April … only the work.
March is the very worst here, for weather. You’d think the beginning of the transition to Spring would mean a lessening-up of awful stuff falling from the sky. You would be wrong-o. The worst snowstorms happen in March - a week later, it’s 40 degrees and sunny - three days later an ice storm knocks out electricity - a week later, yet more snow, mixed with freezing rain. March sucks… Almost as much as August, when the garden is starting to fade, the lawns turn brown, the air is like a boiling hot sweaty blanket, and you can hardly breath for the humidity. So I vote for March AND August. (It often stays hot and sweaty into September, stubbornly refusing to cool down, but its a desperate kind of heat and humidity. You can sense it flailing around, screaming ‘no I don’t wanna go!’ But it does, and good riddance.)
SAD is the worst in December, when the sunlight is declining to its minimum. January is on the whole just as gloomy, but it comes off better in comparison to December because of its increasing sunlight. I was on very bad drugs (interferon+ribavirin) 4 years ago. The physical and psychological side effects of this medication are very heavy. I started the course of it in September, and the worst of it hit in the months of December and January. Since then, SAD has gotten me down every December as a bad drug flashback. It had never bothered me before. This year I had a bad November too. I hate the gloom and I love the sunshine and springtime now more than ever!
I picked January, but only because I couldn’t vote for a tie between December, January, and February. I don’t understand how entire civilizations could have formed in places as cold as this.