Hellcat is faster and has no misfire bug. Wolverine has much better penetration against heavy tanks but with both you'll want to flank anyway. Hellcat has MG upgrade and can cloak. M10 is better at crushing infantry due to the way it can turn sideways very rapidly and seem to slide over infantry. They both have the same vet.
Hellcat is the clear choice vs PE, where you'll use the better speed to sweep through and defeat his vehicles. M10s are usually preferred against Wehr because they are much better against Stugs, P4s, Panthers and Tigers but the misfire bug still makes it a tough choice.
