Pointless. All melee attacks take a person down in two hits, except the hammer which takes three. The pistol is the best because it has a slightly faster recovery time. The shotgun is second not because of it's actual melee attack (Which is no better than any other weapon) but because it is a one hit kill at close range, so even though you are firing, it is used like a melee weapon. The chainsaw is most peoples obvious choice for the best melee weapon, but it leaves you too vulnerable. It gives you the impression that you are invulnerable, but in reality you are frozen for the entire animation and only invulnerable for a small part of it. From the time you raise the chainsaw until it actually starts to slice, you can be damaged. Once the slice is over and you pull the chainsaw back, you are still frozen and can be damaged. If you chainsaw one guy in a group, you will either be chainsawed yourself, or his buddy will stand next to you with a shotgun and wait for his chance to turn you into hamburger.
A boomer melee sounds convincing. It gives a nice thunk. But if your intent is to melee, use the pistol. Or just roadie-run shotgun them. Or rollie shotgun them.
Three shots and a whack from the pistol is a down.
Did I mention I play Gears a lot? It's my new shooter. It replaced GRAW.