I haven't tried the Avenir Sticky Fingers pads. For me, the advantage of KoolStop pads is the tremendous variety of shapes they offer. I've bought three or four sets of the replacement pads they sell for old Campy (and other) brake shoes:
Assuming the shoe is open at the back, you just slip out the old rubber and slide these in, for a look that's as close to authentic as you can get.
And, I see on the Harris site that they now offer these in black too. But, they say they don't stop quite as well as the salmon. Wonder why not. I still have some Mathauser "salmon" colored pads, figuring I'd replace my Nuovo Records, but haven't needed to, yet.