in terms of base damage, damage per second, cost to repair and difficulty of finding weapons to repair it with oh and how awesome it looks or sounds when being used

I'm a fan of the Riot Shotgun, and I believe there is not much that matches it in terms of Damage Per Second, at least for non-unique weapons. It's costly to maintain, but Jury Rigging helps to solve that problem.

With the Shotgun Surgeon and And Stay Back perks, the Riot Shotgun is a [censored] instrument of death. Jury Rigging, as always, solves all your maintenance issues.

For raw power, however, the Sprtel-Wood and the Avenger are unmatched. At level 50, with all appropriate perks, you'll be pitilessly mowing down any piece of [censored] that dare cross you path. Making swiss [censored] cheese out of deathclaws.

I'm partial to Christine's Sniper Rifle, due to its immense critical damage and silencer. Sneak attacks are lethal.

Gobi Campaign Scout Rifle - special sniper rifle! I use it on all my characters! Best weapon (in my opinion) period!