Imo, Zoro. I didn't care for Luffy and I disliked Sanji. Zoro was my third favorite SH and it wasn't for his fights or because I thought he was cool, I thought he was funny, I admired his dedication like being stuck in a wax statue not being able to cut it so spending arc after arc training until he finally could cut from any unfavorable position.
Bur as the series went on, he is no longer funny he doesn't even hang out with the straw hats that made him funny like Usopp and Chopper, he just hangs out with Sanji constantly fighting over who is stronger.
Plus he just overcomes almost all his obstacles without much problems