I have an F90 and my nephew has an F80. I've had a bit of seat time in both, and the M5 is just way better from a comfort stand point. The increase in power and speed goes without saying. The M3 is like a gokart on steroids and feels (in my opinion) more of a connected driving experience. I daily my M5, and couldn't imagine doing that in an M3. Just my .02
