[GuyBFF]

There's no way to identify a "better" clamp. When I purchased mine I had two different styles from the same bin when I made it home. They are stardard Triden units from the Home Depot, but I noticed that the one with the larger crimped section, which in turn was smoother overall required less tightenning to be leak free. I returned the others so I had all the "better" type.

As for high end clamps with smooth insides, there used in commercial transport trucks for exhaust and cooling uses, but I haven't found a cheap supplier.