The whole "Governor's make better Presidents" argument is kind of hamstrung by the fact that Obama was the first Senator to be elected President since JFK. The sample size of Senators turned President to date is exactly two men in 56 years, and one of them only served one half of one term.
I would call it inconclusive. For whatever it's worth (not much), Obama has been a better President objectively than either of the Governor's who proceeded him.
I'm not sure how Obama is objectively better than Clinton.
Obama was able to pass his health care plan for starters. Obama has also been much better than Clinton at defending his agenda from a hostile opposition party that controls both houses. I don't expect Obama to be signing a DOMA type bill because "well, they could have passed worse".