The E1 is my least favorite of the ones I've seen. The finish is strange, like it's too smooth. It also has a pretty decent amount of receiver wobble.
The A&K is the most solid out of the ones I've tried. It's quite heavy, so I'm guessing there's a lot of cheap, heavy materials in the alloy that it's made out of. Still, it's probably my favorite.
The G&G is incredibly light, but also has receiver wobble. I run my G&G as my primary rifle now, it's quite durable, it just doesn't feel it.
It all depends if your mind automatically assumes heavier=better or not. I know that the heavier ones aren't better just because they're heavy, but part of me can't shake that assumption
