Was just musing over this. I think I have 3. Servalan isn't in the list. Though she's deliciously evil. And for the record I vastly prefer Travis I to Travis II.
First up has to be Avon. An anti-hero in every sense, and also a computer/hacking expert, which young me who was rapidly falling in love with computers could relate to. I'm not convinced by his depiction in the later series, though he's well acted. But yup, best one.
Next for me Cally, though she's frustratingly underwritten for, along with Jenna. But among the female characters she was easily my favourite. Even if we didn't always know too much about her. Brill in Sarcophagus of course. I loved both Tanith Lee episodes.
Then although young me really liked the attitude of Soolin I'm going to go with Vila. Always funny, consistent in everything he did. And a great foil for Avon. Under appreciated by his crew mates.
Pondering all this reminds me of last year when I was playing a text adventure / parser interactive fiction game version of Blake's 7. That did an *excellent* job of capturing some of the characters' personalities. Not least Avon and Vila. Though Cally was barely represented. Pretty much like in much of the TV show sadly! To read more about my playing experience with this game
see my writeup on the intfiction forum.