I don't know what my favorite is, I never get to play...they always shanghai me into reffing.
My favorite PC in my games so far has been the "Humanitarian" (An agent trying to smuggle weapons to a pro-imperial resistance on a balkanized world). He had a crate "medical supplies" (Actually ACRs) marked "Biohazard" that he was transporting on the PC ship. The rest of the players didn't trust him and sure didn't believe he had humanitarian supplies, but they were too afraid to open the box and find out.
If I ever did get to play, in T20 I'd probably do some multiclass of rogue/scout/belter/agent.