Ranking my favorite regular characters, regardless of writing/direction/etc:
Spock
Kirk
Picard
Data
McCoy
Worf
Ro
Riker
Scotty
Holograph Doctor
O'Brien
I'm a weird Trekkie, I know everything there possibly is to know about TOS and TNG (including novels, behind-the-scenes stuff, geeky stuff, etc), but almost nothing about the rest . . . I did watch many episodes of DS9 when it first aired.