TWOK for me, too. Larger-than-life action. Over-the-top villain. A great sequel to one of the best episodes of the series.
I liked Trek e're I watched re-runs, but I loved Trek after watching TWOK for the first time in theaters.
I was too young to understand TMP, so it didn't really appeal to me until I was in my late-20s. III and IV were good, but not as stunning as TWOK. V was, well, the worst effort of the original cast (and even more disappointing, when I read what Bill Shatner's original intentions were). The Undiscovered Country was a close second, for many of the same reasons I liked TWOK.
Generations was fine, but killing Kirk in such an anomymous and casual way just brought it down a few notches. First Contact and Insurrection were the best of the TNG efforts, and Nemisis was okay, but certainly nowhere the quality of the other TNG films.
The funny thing is, just a little tweaking on both Final Frontier and Nemesis could have made them among the best of the movies.
Davy Jones
"Frightened? My dear, you are looking at a man who has laughed in the face of death, sneered at doom, and chuckled at catastrophe! I was petrified."
-- The Wizard of Oz