Heavy Bolter

The Vengeance Launcher is fluff now! I'll take one and a combat knive..

I'd have to pick the Bolter, just for sound alone.

Not too mention it's pretty lethal in general:

Cyclone Missile Launcher


It's destructive power is simply overwhelming.

Back in the day, I had a misfire, all missiles went of in a straight direction and wiped out 1/3 of my foes Ork army in turn one. He was not expecting that one

But to name a single weapon as favorite is difficult, there are so many awesome weapons!

Black Sword or Crozius.

Wolf claw and thunder hammer

Power fist and Plasma pistol are my weapons of choice for sure!

but since i'll be playing as a Apothecary, Power Axe and bolt pistol

Heavy bolter and Thunder Hammer

The chain sword is the best realised in terms of aesthetic. It's a perfect synergy of practical implication in the game and aesthetically enriching the atmosphere and tone of 40k. The spacemarines, eldar, Ork would seem less unique from other Ips if they were using simple cutlasses. So I believe.

Its so hard to pick Melta or Powerfist.