I want to go with True Lies, as others have said it's a perfect blend of action and comedy along with some spectacular special effects, but it's 30 minutes too long and the middle plot with JLC doesn't really work. I watched it Sunday in tribute to Bill Paxton, and it's great but not perfect.
And props to The Abyss, where the lives of his cast were less important to him than his film. It just never really clicked for me, though. In fact, The Making of the Abyss is better than the movie itself.
I therefore have to go with T2. It's such a damn fine bit of film-making. Arnie as the surrogate father to the kid gets way too cheesy, but damn, everything else is spectacular.
None of the T squeals did anything for me (although the pretty blond Terminator certainly did).