Personally, I'm quite fond of the heavy assault rifle. The plasma gun's great too, but there's something fun about bombarding a Revenant or Mancubus with an endless stream of micro-missiles until the mighty demon falls like a sack of potatoes.
It kinda felt like that in Space Marine, too. I mean, the execution-for-health-restore mechanic WAS pretty cool, but sometimes I was thinking "OMG guys, do I really need to watch him shove a chainsword through that guy's chest AGAIN?"
