Strangely enough, I was thinking of posting a topic along these lines; the last time someone did, it got a huge response, and now that we have more members it'd be interesting to see the opinions of more people.
But it looks as though I don't have to now, Oddite's said it for me!
My favourite creatures are the Glukkons. When I first got AO, the Mudokons were my favourites, simply because they were the 'good guys' (even though we now know that all the races are innocent in one way and guilty in another). But I thought the Glukkons looked pretty cool, and I wondered what they could possibly look like under their all-concealing suits (I got my answer in the good ending FMV, though). They only really appear in one game screen besides the FMVs in AO, so they're not a ludicrously important component of the game. And only one Glukkon (Molluck) is really put under the spotlight; the others are just walk-on extras so you don't really pay much attention to them (although I like that one in the green suit in the boardroom, who says "My God, Molluck, what are you gonna do about it?!" when he sees the screen full of plummeting profits).
In AE, the Glukkons play a much bigger part in gameplay, and four individual ones with proper names and personalities make an appearance, and I decided I liked them a lot more. The Sligs also get more speaking parts in AE, and so they become more interesting as well (although their mysterious silence in AO was quite effective; I think I respected them a lot more in AO than I did in the slightly cheesy AE).
So, in descending order:
1) Glukkons
2) Sligs
3) Paramites
4) Elum
(3 and 4 are pretty much interchangeable; on some days I prefer Paradudes, on others I prefer Elum)
5) Slogs
6) Mudokons
7) Scrabs
Meeps and Fuzzles look pretty cool as well, but I want to see them in gameplay before deciding how much I like them.
Onto characters, my favourite Glukkons are definitely Phleg and the Brewmaster. Aslik was my favourite when I first got AE, because he's quite good-looking as far as Glukkons go, but Phleg exudes much more personality, and he's so endearingly and irresistably ugly. He also makes the most appearances in FMVs (he gets four; Aslik and Dripik get three; and the Brewmaster only gets 2, or three if you count both endings, but you can't view them both in the same game without using the cheat).
[ November 30, 2001: Message edited by: One, Two, Middlesboogie ]