Flying Sandhawk is the best. You want faster bullet velocity so you can actually hit things before they move. The normal bullet velocity on Sandhawk is painfully slow. Also better fire rate... and everyone should know by now DPS in this game is all about fire rate.
The amp damage of the Bee shield accounts for like 95% of your damage. This makes the damage difference on the actual gun (stopping vs any other variant) completely insignificant.
I'm pretty sure even the faster reload variant is better overall DPS than damage, just because you reload so often with that gun.