I'll take the opposite opinion.
I found that the AvP1 multiplayer was much better. Sure, Predators were bullshit, but the Marines and Aliens were fairly well balanced. And while the SP was really, really tense, the spawn locations of the Aliens didn't change that much - it was generally the difference between spawn location A and B. So one could memorise those, too. Plus, the plot of each campaign was really weak. The Predator campaign basically ended three levels in, with the last two/three missions just being "hunt some dudes, k?".
AvP2, on the other hand, had the most convincing AvP storyline ever imo. The environments had a great sense of codependance, too. Plus, having a section in both the Marine and Predator campaigns where you lose all your stuff was a great move. That game understood that raising the stakes sometimes means punishing the player, rather than upping the enemy.
The multiplayer balance left a lot to be desired. I certainly had heaps of fun times in AvP2's multiplayer, but between all the abusable Marine and Predator weapons, there was just too much shit going on for the experience to be consistent.