Fat scout, hands down. I have a personal hatred of using the Vulcan and you won't catch me using one. As for the Hawkins, I don't have any first hand experience with it, but I know you can't get up close with it and be a beast like you can using a flak or vulcan.
Edit: Now that I've used the Hawkins on my Brawler, I'd still say the Flak Cannon is my favorite. The Hawkins doesn't do as well in close combat as the flak, and it's harder to use at a range without the sharpshooter's scope. That's just me, though. I tend to favor burst weapons more since my aim is really shaky, and it's hard for me to keep my aim on someone longer than a second. Again, this is all my opinion.
As far as viability goes, on the longer range maps (Last Eco, Bunker, Front Line, Facility, Bazzar) the Hawkins is the best bet. On closer quarters maps (Wreckage, Origin, Uptown, Prosk) the Flak or the Vulcan would work.
					
					
					
							Edited by SoldierHobbes11, May 07 2014 - 02:34 PM.