Shooting clays is more the individual and if they can hit the $&%(ing clay in the first place. I'm struggling with the concept of 'leading a target'.
The perfect clay buster is the one you can use to bust them with. I was out with a buddy of mine this last weekend and we shot 3/4 of a box of clays. We are not that good but we had fun in the pouring rain. He has a 930 Waterfowl with a 28" ported barrel and I'm running a JM Pro with a 22" barrel. When on target, both destroyed the clays equally.
@tarster runs a 20 gauge 870 that's older than dirt and does a fine job eliminating the flyers. An old side by side I had did a reasonable job eliminating clays when I could hit them with a 20" barrel.
The differences you seek are not accuracy, it's cycle rate and what type of recoil/gas system it has (gas/inertia etc). A $125 single shot will do the same damage when used properly as an expensive Benelli.
I run a 930 because I need the semi auto soft recoil for the shoulder, not because I want fast follow up shots.