I don't know where you get the impression that the minigun is pathetic, unless you're taking armour into account, in which case I'd also contest the power of the rocket launcher.
Though 'strongest' is a very black and white argument, it measures raw power. However the 'best' weapon is, arguably, the Alien Blaster, being able to tailor your character to make 6 unaimed shots, or 3 aimed shots, with incredible power.
I'd also personally pick the Ripper over the Super Sledge (BoS Hammer?) as I find it has a greater knock back potential.
Minigun does 4-5 damage against my avatar with Combat Armore. And anybody remember the mess of entering the Mutant Base? They got 3 Super Mutants there, 2 with Miniguns and 1 with a Rocket Launcher and AP rockets. I remembering entering that base several times, easly dieing against the Rocket Launcher several times. And i dare anybody who is not using Improved PA to dare say they did not attempt to kill the guy with the rockets first.
Hmmm, never really tested out an Energy Weapon char with the blaster so would not really know. But it does sound powerfull. Also the TPA sounds powerfull, but not really tested so.....
My choice on the BoS hammer against the Ripper? I just got to say Burst to the Eyes for that argument. The Ripper also requires Power Cells, and the Hammer got 2 hexes range. I say they are about equal, but the Hammer does have a small edge.