I'm not really a big fan of Star Trek in the sense of episodes and characters, but more so the Star Trek universe in general - the ships, the races, the exploration of space.
I enjoyed most of TNG from the third season onward, as well as most of DS9. I never really got into Voyager that much, but I think I've seen most of the episodes by now. I watch Enterprise and some of the episodes are well done, but I'm really tired of the whole time-travel thing. I wish they'd stick to stories like the Vulcan-Andorian conflict, Romulans, exploration, things like that - those stories seem to fit better with the way I think of Pre-Federation times.