Since the first time I saw a heavy bolter in a computer game, there really has not been anything that I find as pleasing. The constant chatter of its nonstop singing as the purifying bolts are sent forth on their missions of cleansing is sweet music to my ears.

Thunder Hammer... And if they made a gun that shot Thunder Hammers, that's what I'd use.

For guns though, I suppose the Assault Cannon would rank right up there. Something about ripping through thousands of rounds of ammo in a very short period of time is just...satisfying.

Sniper Rifles and Lascannons.

Power fist and combi-melta

Plasmagun for ranged then a thunder hammer for close. you cant do much better then melting heretics down to molten plasma.

The Holy Bolter and Chainsword.

When I was reading about different stuff on the wika, I found this and I hope you like it

• Magyar - Magyar is the venerable, current Chapter Master of the Mortifactors Chapter. His exact age is unknown, though most would guess his age to be at least 700 Terran years. Physically, Magyar cuts an impressive figure; his eyes are dark pinholes which seem to swallow all ambient light. His long, silver hair is tied in numerous crystal-wrapped braids reaching to the small of his back and his coal-dark skin resembles a lunar landscape, cratered and ridged with innumerable wrinkles. A long, forked white beard falls to his waist, waxed into sharp points. He is clad in Artificer Power Armour made of bleached bone; the breastplate is formed from long ribs, bent and fashioned into the proper shape, the Imperial Aquila at its center as skeletal as the winged familiar that sits atop his throne and watches the proceedings below. Every piece of this great warrior's armour, from the greaves to the vambraces, cuissart and gorget is formed from bone. He carries a gigantic Power Scythe into battle, its blade silvered and sharp, the haft gleaming ebony.

http://warhammer40k.wikia.com/wiki/Mortifactors

Well there is the Scythes Of The Emperor. They might use power scythes.
http://warhammer40k.wikia.com/wiki/Scythes_of_the_Emperor
http://wh40k.lexicanum.com/wiki/Scythes_of_the_Emperor

E-Claws the best thing to cut ur meal

I recalled reading about the Mortifactors in the Ultramarines novel "Warriors of Ultramar." Though it has been a while since i read that book and I don't really remember those guys to much. Cool guys nonetheless.