You should be asking if Verizon is a better choice than Sprint before worrying about phones. I would say the 9500 is the equivalent of the Sanyo 4900 on Sprint in terms of quality and reliability...whether or not it is "better" is a lot more subjective though.
I would probally say that the equivalent phone that sprint carries is the samsung a500 or the sanyo 8100 Jack
The a500? That phone has a history of problems, something the 9500 does not. As for the 8100...aside from both having excellent screens, I think the comparison ends there. As far as size and form is concerned, the 9500 is most similar to the Sanyo 5300 from Sprint. I still think the 9500 compares best with the Sanyo 4900. Both get fantastic reception, have a good track record, and both phones have slow processors that make some games and applaications run like molasses. Of course, the 4900 gets about 4 hours of talk time, as opposed to the 9500 that gets 90 minutes or so with their standard battery.
Matt Compairing it to the a500 in terms of screen resolution, ease of use etc. I know that the a500 has had it share of problems but remember that it was one of the first vision phones. Size wize 5350 is close or the 5300 Jack