Hate to get into ranking discussion but....
TOS - Watched in full, but no interest, generally not a fan of older television shows
TNG - My favorite for the cast/characters
DS9 - Decent overall, but didn't quite like the overall tone and religious aspects
VOY - Liked the overall tone, the technology aspects and the overall story of returning home, but didn't like some of the cast/characters
ST:E - Somewhat interesting but kind of fell flat
So for the next show I'd like something with good characters/actors, set in the future, and good overall story arch. Not much to ask