The worst part about Ambipom - no seriously, the worst - is that it has all of those weird details, like the bloated, diseased hand-udders, weird grass-hair, a fluffy purple bottom, are brought together into true horror by that frozen, empty smile and eyes. That thing is fucking creepy.
I like Drifloon because it's so unassuming. I think what I like most about it, though, is its Pokedex entries, which imply that it steals children who mistake it as a balloon. Don't worry about me, I'm just a derpy purple balloon with these bright, heart-shaped yellow tags held at child level!
You are indeed correct that Drifblim is a terrible name. I know what they're going for, but jesus stick another vowel in there or something please? Drifoblim? Drifbloom? It's really uncomfortable to say that name. The Pokedex says it carries people. It doesn't say how or where, though. Makes you think. Try not to think too hard, though, there's only one apparent hole in this thing. Well, two, if you don't assume the X-bandage in its face is concealing a horrific tunnel of pointy teeth.