So far I've been really happy with a GSG 522 I bought.

It's an MP5k with the foregrip replaced by a front RIS system. I've been finding it fantastic, and the Hop-up is strong enough that all the way off, out of the box it was shooting .25s with over a 10ft upward curve. After a couple hundred rounds through it it's leveling off nicely. Extremely impressed with the ROF and side folding stock style.

After a game in a couple weeks where I'll be really putting it through its' paces, I'll be writing a review. I've had it to a few games, but due to the break-in period on the hopup I can't say with 100% certainty on some things yet. My new optic should fix that. I'm going to blow through low / midcaps though.