In my opinion, I agree FUZION PREDATOR, the original 1999 AvP was the best for me in terms of overall experience even tought I played AvP2 much more (mainly due to the mods eheh and awesome people)
Avp3...shhhh....maybe I didn't give it a shot, but it felt like a rushed game, and I have to disagree with you Acidglow, I liked the standard melee combat from earlier game than this wierd block and heavy attack,etc system, but thats me. Also avp3 lacked good maps(they dont even a decent vents for the Aliens), and lacked modding support, and marines, god, they were soo...I dont know how to describe, they didn't felt good for me, rushing in, no gear whatsoever, no helmet...
Just my 2 cents.