1. TOS A++++
Kirk, Spock, Bones, Scotty, Sulu, Uhura, Chekov et al, I will always love you!
2. VOY B+
I guess I just really connected with the characters, and we got a sense of exploration back in Trek.
3. TNG B
The first two seasons are my favourite - let's see what's out there.
4. ENT B-
Seasons three and four are excellent.
5. DS9 C+
The tediously overlong war and religious overtones really brought the show down for me. I certainly don't dislike it though.