Of all the Trek films, there are only four that I could watch over and over again without getting tired of them: STII, STIII, STIV, and Star Trek (2009). And if I had to choose just one of those four, I'd choose STIII.
I can't agree about ST2009, but ST2, ST3, and ST4 are the original trilogy of the Star Trek universe. I agree they are the best 3 star trek movies, taken as a whole. I never get tired of them either. Star Trek 2 is the most serious, Star Trek 4 is the most light hearted, and Star Trek 3 is the most well rounded IMO. It has a great balance of fun and drama. Star Trek 2, having the more skilled director, definitely feels the most "cinematic" though.