As far as "experience", obviously Sarah Palin.
However, "qualified" is not a specific term.
Constitutionally, both are qualified, as the only requirement is age. No question there.
Technically, neither are qualified, because neither have been elected or appointed yet.
I would like to comment here that the original Constitutional method of choosing Senators was in the hands of the State Legislature, and was totally non-delegable. It was the 17th Amendment that gave people the vote on that.
The reason the founders wanted Senators chosen one more step removed from citizens was to make it more likely that Senators would be the most experienced people available, a source of wisdom and restraint.
I'm not certain either would be on their respective state's "short list", but Kennedy certainly would not.