MJ, of course. Never lost a Finals, and won all his championships without an elite big man like Shaq or Pau Gasol.
That said, I do think it's a little unfair that the comparisons between Kobe and MJ diminish Kobe's accomplishments in many people's minds - Kobe may not be the greatest player of all time, but I'd say he's had the greatest career of anyone in the Post-Jordan Era so far.