Recommendations for a set of 3rd party AF extension tubes?

It would be great if forum members with first-hand experience with 3rd party AF extension tubes for Canon EOS (such as those on offer at a very large well known international auction site) would like to share their recommendations and observations from using these with heavier cameras and lenses.

I´m trying to find a cost effective set of AF capable extension tubes with very little slop, properly light absorbing interior walls and zero light leakage from the outside.

(Thanks to kind input from forum members in an earlier thread I´ve found a set of great low-cost non-AF extension tubes, and now I´m looking for a set of AF capable ones.)

BR,

David Svensson