I saw Predator for the first time last weekend, and it was awesome! A very well done, satisfying film! Also, I hadn't really liked the plasma cannon as much up until now, but after seeing it I like it a lot more!
I'm having a hard time choosing between Predator and Predator 2, because they're both so great -- a perfect duology, just like Alien and Aliens. Overall, I think Predator is the better film, but I have a more personal connection with Predator 2, it being the first film in either series that I saw all the way through and having only recently learned about it, being too young to see any of them unedited (it was on the FX Channel, around 2004 or 2005, and it aired after Alien both times), so I'll list that one as my favorite. Thus, they're both the "best"!