Just finished watching the old Trek movies (pre-TNG). Apart from 2 and maybe 6, nothing like that will be made today. Too slow for a major release. And the actors were and looked too old.
Based on how much they were like Trek (and whether they were any good), I'd go:
3 1 6 2 4
(didn't see 5).
1 in particular was painfully slow but was a nice idea that could have been done with about 10 minutes less of shots lingering on the hull of the Enterprise. It was like a decent TOS episode shot on a big budget, and following a Trek tradition there is no action climax.
2 stands out from the rest as an action-driven movie with some ok character work, and a memorable end.
3 was the perfect adaptation of Trek into a movie form IMO (Kirk and the others' commitment to Spock, the hubris of the genesis machine, and the added excitement of the Klingon threat.
4 was a stupid concept done semi-seriously. Also a very on-the-nose environmental message.
The message from 6 couldn't have been clearer, given that it was released as the Cold War was ending. (They literally use the words cold war and gulag; the Klingons have destroyed their economy and environment to compete militarily). It's an excellent send-off to Kirk, Spock, and the rest*, and it's made explicit that they're passing on the torch to the ummm next generation (Worf is involved). But one of the villains was very obvious even though I think that was supposed to be a surprise.
*Generations and STD and the reboot aren't real.