TOS: McCoy (a curmudgeon who secretly cares about everyone---the way I see myself, basically

Spock is a very close second place)
TNG: Picard (no close second, although Data wasn't too bad)
DS9: Worf (O'Brien is a very close second, and I love Odo, Garak, and Quark)
VOY: Kes (the ultimate Trek character---hopeful, curious, selfless, brave---no other contenders at all, really---they ruined the EMH for me

)
ENT: Phlox (absolutely no other contender...well, Trip was okay...)
TAS: Spock (his lovable know-it-all attitude was even more on display here than in TOS, so I gotta choose him)