I would like to change my previous post: my favorite weapon will be a scoped combi-bolter with plasma or flamer attached.
Veteran Sternguard holy weapon of badassing!

Crozius Arcanum.

Chainsword is my favourite, just seems so iconic for the Imperium. A brutal weapon for an equally brutal future.

Power axe and melta gun

Crozius Arcanum, always the chaplain, I want the heretics to see their deaths reflected in my face.

Bolter and chainsword forever
Maybe carrying also a flamer. It will cook the dinner

The Manreaper power scythe was a loyalist weapon used during the great crusade and was most commonly used by the Death guard legion though I believe it is still in use in current times but less wide spread, I think it's still manly used by chapters such as "Scythes of the Emperor" however I could be wrong

Thanks for the info. I just think if chaplains (mainly Dark Angels chaplains) use Scythes, they'd be so kool.

A scythe would certainly look great on a wolf priest also, but I'll stick to my crozius arcanum...