Given the choice it's AAC all the way. However there are very few manufacturer's doing AAC, Enya have it with a couple (I have the AAC Enya 60X) and Jett have it as a high performance option on some of their engines (as if they aren't high performance enough already ).

One of the benefits of AAC is that the liner doesn't stretch at the top as ABC liners do after some time so they keep their clearances (last longer).