The new Toto tornado flush toilets do an exceptional job of scouring the toilet but you get a slightly smaller water patch which bugs some folks. Water patch is the area of water in the bowl.
Regarding flush volume, remember that a toilet does not push everything down the drain. It sets up a siphon in action pulling the waste into the sewer line. Toilet lines are now 3” by code as opposed to the old 4” lines so they actually flush better and carry more waste with less water.
If you are short so lifting high enough is a problem and don’t have anyone to help you set the toilet on the floor bolts, a waxless ring is much more forgiving than a traditional wax ring.
I have that one, and I like it, too. … If I ever got another toilet, I would get one of the pedestal types without any curves and caps on protruding screws, the kind that need finicky cleaning. The pedestal type is so much easier to clean off. … be darn sure if your toilet is in a bathroom upstairs that the wax seal is in perfect condition, the slightest crack and water is going to leak underneath and stain your ceiling and wall below.
I don’ know the OP’s age or health situation, but if you are getting up in years or have trouble getting up and down from a squat, and you don’t have young children, consider getting a taller toilet like in the handicap stalls.
We have a short toilet and my wife just had a knee replaced and getting on and off a short one was a problem. So we had to get this donut adapter that goes on the seat. Hate, hate, hate trying to shit through that thing. Second knee replacement is coming soon and I dread using that thing again. I have a small house with only one bathroom, but if I had two bathrooms one of them would have a tall toilet.
I think they sell replacement seats that are taller than the usual type. Might be better than the donut, but not as good as a new, taller toilet.
Like someone said upthread, there is a difference among the “rough in” measurements, meaning the distance from the wall (the wall, not the baseboard) to the center of the drain pipe. I don’t know them exactally, but I think they are 10", 12" and 14". I think the 12" is the norm. In my house I had two 12" but one was 14" I believe, and finding that to match the 12" was a bit of an effort.
Other than that, it’s really very easy to do this, as long as the bolts alongside the drain pipe are solid.
This is the part that will catch you. Everybody knows you don’t just replace the toilet, you always end up redoing the entire bathroom. Have fun!
12" is standard and has been since sometime in the 1920s. Before then 14" was standard. The toilets back then had enormous tanks and were usually connected to the bowl with a bent pipe, so they needed some extra room. Something like this: Top 5 Tips for Caring for a Vintage Toilet New toilets made for 14" rough-ins are more likely to just have an extra-deep tank but the same base as any other toilet (less engineering required for that). Or you can put a little shelf behind it. The 10" toilets seem to be more anomalous, generally for tight situations where floor joists are in the way.
Like @tofor said, IF the bolts are solid, that’s great, but it’s still a lot of work. If the flange is broken then you’re in for a world of hurt, doubly-so if the drain pipe is cast-iron.
There is some variation among “standard” height toilets. We had two replaced in the same year, but one is about 2’’ higher at the seat than the other one. I’m a long-leggety critter, and I would have preferred a higher “handicapped” model, but my wife is a foot shorter, so that was vetoed.
BTW, those who bought a new toilet; did you go as far as sitting on the display model at the plumbing showroom? Because it seems awkward to do so, even fully dressed, but something you might want to do to decide if the height is comfortable.
We have a Kohler and a Toto, both less than 10 years old. The Kohler is dual flush. The Toto is not. The Kohler I wound up adjusting to flush more strongly, and have no problems with getting stuff to go down since then. The Toto has no problems. Both of them require a little extra use of the toilet brush compared to our old ones, but it’s not a big deal. But if I were buying now, I’d look into the options that wash down the bowl better.
The Toto replaced a toilet that was clogging all the time. It still gets clogged rarely, but it’s because of two 7-year-olds who sometimes use half a roll of toilet paper at a time.
The Kohler is much, much louder than the Toto.
We also bought a bidet seat for the Toto, which is great. It’s not a perfect match, but was way less than getting an all in one. Plus we weren’t sure how much we’d like it.
I wish we had. If so we would have discovered that “chair height” means that the toilet is just tall enough that neither I nor my late mother can (could) put our heels flatly on the floor…
When my friend was 3 years old, he went as far as taking a crap in the display toilet at the hardware store.
I didn’t sit on them in the store, but I made a point of noticing the difference when I was out and about.
Louder on the flush and/or the tank refill?
I am not very fussed about a loud flush since it is over in a few seconds and usually the door is closed to mute the sound outside of the bathroom but I prefer the tank refill to be quiet since that can take a minute or so and often the door is now open to the rest of the house.
This made me laugh wayyyy more than it should have. 
That requires having a power supply near the toilet, so that’s a consideration in choosing something like that.
My personal opinions on the topic in general:
Do toilets vary in height? Most of them are too damn low (I’m tall) so take that into account.
Bowl shape. Never had an elongated bowl until this house, and they’re a pain if you have to plunge them, but overall I’m pleased.
Much louder flush. I think the refill is louder, too, but not as much louder.
I would suppose that the taller toilets designed for elderly people would be a good idea. Might as well start preparing the house to “age in place.”