My favourite movie (in case anyone hadn't spotted this already) is The Terminator - well actually I like the whole franchise. I'm hard pressed as to whether I think #1 or #2 is better tho. Both are pretty solid films, although I have to say that the second one has the most memorable lines - especially from Arnie.
The only real problems with #2 is the rather silly idea of "liquid metal" and the massive temporal paradox it leaves us with at the end of the movie. Because by destroying future-Skynet, it means that the war will never happen, no Terminators or Kyle will be sent back, John won't be born and Skynet won't be built based on Terminator bits. So end result is both the first movies disappear in a puff of paradox.
#3, despite being the worst film so far, goes some way to fix this. By suggesting that Skynet is inevitable in some form or other it makes it still possible for a Terminator & Kyle to be sent back to kill Sarah/unborn John. Although the ones that get sent back after #3 aren't the ones from the #1 film. Instead they're sent back to an alternate past where #2 doesn't happen and the original timeline Skynet is created and then things happen as we expect in the first 2 films. Sounds complicated...I wonder if I could draw it out as a diagram?
Anyway, #4 is a totally different kettle of fish compared to the others. It doesn't involve time travel for a start. But you know how (for the most part) it ends cos some of the characters have to be still alive for the aforementioned time travelling shenigans to happen. It's a lot better than #3. It also makes me squee lots cos of the first T800 that appears towards the end.
PS I think the Sarah Conner Chronicles was also a pretty awesome TV show and I left it out from day 21 *sighs*