There's a forum dedicated to Chinese lasers here Laser Engraving & Cutting Machines - CNCzone.com-The Largest Machinist Community on the net! but I can tell you that I have a WK Laser machine from China that I've had for over 4 years. It's a good laser and the after sales service has been excellent, in my opinion.
Check the laser forum for info on other brands that are good also. Lots of reading there to keep you busy for awhile, but I don't think that many of the glass tube Chinese lasers are used for cutting metal.