It is cheaper for our institution- of course we are higher education which Microsoft gives a big discount for- VMware does not. I talked to many folks in industry recently though and they say Hyper-V is cheaper for them as well though. The benchmarks give ESX a very slight edge in speed, but it's not much really. The only feature ESX has that Hyper-V doesn't is USB pass-through and VMotion (which is in beta for Hyper-V).