I'll also vouch for the KJW M9. It was my first GBB. It's seen thousands of rounds. Other than the mag catch wearing out, the gun shoots hard (about 310 fps) and is extremely accurate. The down side is that the mags tend to leak after a while. But the gun itself is excellent. I hear the newer generation models will accept TM mags, although I know mine won't take them.
KWA are basically KSC guns made in Taiwan instead of Japan. And they come with metal slides instead of plastic. I can also vouch for that, as my KSC Glock is my main field gun. The thing is a beast.
I would't recommend WE unless it's the High Capa. While they tend to break easily, the High Capa is 100% TM compatible, so replacement and upgrade parts are readily available at reasonable prices. Avoid the WE 1911 as they tend to be problematic and aren't compatible with anything, so replacement parts are almost nonexistent.