High End AEG

I have thought about returning to Air soft after my year or so leave of absence..what do you all recommend for an M4 variant?

I have heard great things about the KWA line...

There are quite a few excellent options to go with. I think it's best to look at each one and pick the one you like best, since most M4 variants (and high end AEG's in general) will end up shooting at about the same FPS.

I have also good things about KWA's, G&G's, and I happen to like my CA M15A4 a lot. I would start with those brands and see what you can find that suits you. Chances are that one of those brands has a suitable M4 of a particular type that you're looking for.
-Bob.

Bioniclebert has it right...truth is the guts of these things are all but identical. IMO anyway.