The ThuderH.... erm, Super Sledge all the way. The thing simply pulverizes anything that comes near.
K first do yo VATS? If yes sledge is better, if not then ripper is MUCH easier to use.
I believe it is just a display bug. I have heard from some people that use it it still does the damage and it just does not show up.
I am going to go with a Melee/Minigun T-45 build shortly and will try the Big Leagues perk but I do not know when I get to that level since my highest level character so far is level 15 since I usually play Dead is Dead or quite close to it.