I just watched Predator 2... for the first time... finally. (Some Predator fan I am, huh?)
I like what P2 did to expand the Predator universe, in terms of the types of Predators and the weapons. The main Predator in this one just wasn't very easy to kill, either. As far as the humans go, though, I really didn't want to empathize with any of the main characters. The movie started out as a typical late-80s/early-90s cop flick, and I'm just not a fan of cop movies. It contained the classic old cop movie cliche about some cop who bends the rules, disobeys his superiors, goes on his own investigation, and eventually solves the case by being a maverick. Where have I seen that before?
But back to the Predators in this one. I like the expansion of the mythos that Predators are drawn by heat and conflict, and that they still continue to fight with honor. And the new weapons, like the smart disc, combo staff, and netgun, are awesome. I might just have to make a couple of those for myself. (I've also seen them in the comics, which have provided me a pretty good amount of inspiration.)
I don't really have a ranking of all the Predator films in my head right now. They've all done different things to expand the Predator mythos and given us a playground. And so far, they haven't committed the Predator equivalent of Ewoks, Jar-Jar Binks, or Son of Godzilla.