Picard for me. Leader, role model, scholar, strategist, diplomat, artist, lover, explorer, philanthropist, teacher.
I know for a lot of people there's Kirk and only Kirk, but every now and again I thought he was an arsehole, and I don't think he'd have done half as well without Spock. I know Riker was crucial to Picard on a couple of occasions (notably his recovery in Best of Both Worlds) but I always considered Picard as a man capable of standing alone, and find Kirk without Spock rather... illogical.