I, also, love my AA middy (complete upper). Don't get me wrong, it would Never replace my AK as my "SHTF" rifle, but it's nice. I'll never own a DI rifle, so the AA was my intro into the AR world. I do like it, it's accurate and modular. I'm not a gung-ho AR fan, so I don't share the enthusiasm of it. It's heavier than my AK (by a full pound and equal set up), The DI's long bcg is not needed for a piston system, but since this is a "conversion" system it utilizes it. A piston system could be much more simplified (AK, Sig 556, etc), but remember that these are designed as "conversion" (keeping as true to the AR parts as possible while introducing piston operation). Not the most ideal piston set up IMHO, but it works and maintains the benefits of the AR platform as far as ergos and accessories go.
I honestly believe the Sig556 is the best comparable system for piston merging AR (like) ergos with AK style piston... but if you're hell bent on using AR accessories and basically want and AR without all the fouling that a DI presents... AA or any of the other "converted" version/makers will do the trick.
IMHO, if you want (similar) ergos to an AR, and stanag mag use, Sig556 is the way to go. If you want an AK that uses stanag mags, A 556 AK with m4 mag adapter is way to go. If you want an AR that doesn't foul as much, then a "conversion" piston system (such as AA) may be what you want.
Just my late night .02