I keep a green assault rifle on me that has nearly 35% impact. I'm sure guns are balanced given rate of fire and impact and stability (the other stats im unsure about) but the issue is you've got to find something you can reliably headshot with. A slow (high impact) AR or a slow (high impact) Pulse rifle are the least feast or famine IMO.
All DPS is equal, but a really high ROF will make you miss shots (crazy fast AR), and a really low ROF will make missed shots more punishing (hand cannon) - find a middle ground for effectiveness across the board.
I think a faster AR is designed around making you "flinch" but to be honest the flinching isn't that bad in this game.