For 40mm grenades I've found that Madbull is the only way to go, though propane vs c02 is arguable. As to the brand of launcher, that depends on the gun really. Different manufacturers mount m203's slightly differently. So do your homework and make sure the launcher you're going to get will work with the gun you have. Personally I think the xm203 is ugly. It is also, as far as I know, ris mount only. So if you're after a barrel mount like mine then you'll have to go with a classic m203. You asked about the Classic Army m203, if your gun is a Classic Army then that's a good choice, it'll definitely mount with no problems, otherwise you may have to get an adapter kit. The same goes if you want to mount a different manufacturer barrel-mount m203. The one in the picture I posted is a Classic Army.