The best outright tank is the earth main, but yeah, if we're talking non-main characters, I'd say Kimimaro. Him with a decent healer works great since he constantly gets tankier as he endures hits (like the earth main and Jirobo), works well with Kabuto since Kabuto deals 1dps to the team each time he uses his mystery. Also, let's not forget that Kimimaro deals decent dps with his skill and he blocks the first single target standard attack that hits him. Overall, I'd say he's far better than Jirobo.