Mine is Jimmy, to be honest, I felt like he got the best episodes and was such a strong interesting character. Not to mention the part was so well acted by Josh Brolin.
I'm not a well adjusted person, I just play one on the net.
Honestly, I don't remember all that much about this show. I didn't even remember the title until I decided to look up "Teaspoon".
As a kid, I think I was too young to be able to understand the show. I remember calling it "Teaspoon", so I never actually knew it by its actual title.
So I'm guess by that, that my favorite character must've been Teaspoon... a cowboy, I'm assuming? :)
Jimmy for all the reasons you listed in the first post - great episodes, great lines, well played - he could say more with a look than any other character - even Ike.
Buck, he was the best person on the show. I liked Kid when I watched the show for the first time when I was about 14 but now, Kid just whined all the time.