I think I have to go with the Powered by the Apocalypse 2d6+stat vs 7-9. It is fast, easy to use, easy to remember and has multiple tiers of success. And that is just the dice results themselves; although the choices of how the miss/weak hit/strong hit results are much more controversial but I enjoy the entire "success with consequences".

It does have downsides, for instance you cannot us it in a numbers-go-up system, but none of them bother me too much.