Dart Gun Xuanlong Assault Rifle (free spot: sometimes Lincoln, shock grenade, smg, or melee weapon)
Ol' Painless ----------------- <^v> ---------------------- A3-21's Plasma Rifle
Frag Granade The Terrible Shotgun Missile Launcher
But my favorite is Ol' painless, Lincoln's Repeater, and smg
I live off of Ol' Painless. 100% small guns + 0 spread! + extremely common ammo + ample repair parts = win.
Though, I also like the Xuan Long Chinese assault rifle (have 2600 rounds for it), the terrible shot gun (fun for hunting super mutants in close quarters), and the Blackhawk for those pesky high health long range battles. I also use the 10mm silence pistol to kill radroaches and molerats (gotta use up that 10mm ammo some how, and why alert bigger game dispatching smaller prey).
The lincoln is ok but its the ammo that is so finite even with scrounger that brings it down and since I already use the blackhawk for .44 ammo, its out for me. Also I never really use the A3-21 rifle, people swear by it but it gets just a shug from, me probably 'cause I keep my game pre-enclave.
Also the MIRV is fun but only on an unused save, as it spends so many mini nukes, but oh will it clear out Megaton in a hurry. And I can't wait to get my hands on a microwave emmiter, and finally be able to take on sentry bots with ease.
My favorite is definitely the A3-21 Plasma Rifle, hands down. It's very versatile.
If I had to pick a second favorite, it'd probably be the baseball bat in VATS. There's nothing like an uppercut kill in slow-mo with that thing... o.O
The Metal Blaster, from The Pitt, it's basically a laser rifle shotgun. Also the dart gun is useful for slowing those pesky deathclaws down.
Why the h*ll do you have to bring stuff up from DLC if we don't even have any yet? It's like saying, "Hey, this weapon is awesome. No, you can't have it."