If Sprint coverage does not work for you, you should leave. Things are getting progressively better as time goes on and the network is in a usable state now and speeds are somewhat competitive. Coverage is not going to change significantly until 800mhz, which is not going to happen for a while yet in Rochester.
I'd like to encourage you to stick it out because I'd rather see a Sprint subscriber than any of those other three, but there's no point if it doesn't work for you.