I'm indifferent with KWA, had a brand new USP, trigger snapped after three games.
No experience with KJW, but I disliked their P226.
Here's a gameplay video of my TM M&P9 out of the box @ Mach1 Airsoft. Cleaned and lubed, didn't dial the hop-up in at all, on .25's.
Was in December, cold outside, in doors was about 10 degrees? Didn't have any cool-down issues or such that I noticed, but people running WE GBBR had cool down problems and couldn't cycle through a full mag :P.
Only downside, not many retailers carry TM's for you to hold.. the newer TM's quality on the plastic feel great.