I took a careful look at Volve XC60, but did not drive it, last weekend. Looks pretty good, thinking it to replace my S80 after 2-3yrs.
I think Q5 should be similar with XC60: good driving performance and dynamic, not very quiet and smooth and reliable as RX350, but more fun to drive. Do not even dream both won't have any problems even in first 4yrs.
So, if you want economic, go for RX; if you do not really care $ and like driving fun, try Q5, XC60, or GLK.