For the ranged weapons, I'd have to say that the Bozar is the best. For melee weapons, it would be the Nuka Breaker.

The MF Hyperbreeder Alpha. It's great on hardcoe for killing weaker enemies without wasting ammo.

Sprtel-Wood 9700. It does it all, especially with Max Charge ammo. Massive damage? Check. Massive DPS? Check. Anti-armor capabilities? Check. Awesome sniping accuracy? Check. Badass light show and look? Double-Check. Insane Crits? Check. Over 9000? DAYUM STRAIGHT.

For Guns skill I'd have to say Medicine Stick. Sleepytime would be handy in a lot of situations though and I've heard good things about the Lil Devil.

Medicine stick is one of my fave's, most of them are pretty awesome. Nuka Breaker for melee, it is extremely deadly. GRA fatman cause all those crazy rounds are fun to play with, though I have not found more than a handful of instances you can even use a nuke w/o reloading the game after lol