[Zack The Ripper]

Viper Tech is the supposed god of gas systems. Very pricey, but very reliable. Not highly available in country rifle or parts wise, and mags aren't cheap or readily available either. It can be done, but you'll have to hunt.

Inokatsu I don't know much about unfortunately. Never had any experience with them.

KWA LM4 and the PTS MKM are basically the same system with the LM4 having revisions made to its most recent Gen as these were updates added jnto the MKM. Again, both basically the same platform, the MKM is just prettier. Supposed to be very robust systems with the older Gen stuff being a bit finicky, and the newest Gen supposedly being bang on the money right out of the box. The problem is that KWA parts are not as widely available as they should be given the prevalence of KWA products on the market.

WE Tech has come a long way in the past year. Their product quality and variety seems to have gotten a boost, and there are many more aftermarket parts available for decent pricing. It's a good versatile platform. It's less expensive for stock guns, but doing the minor upgrades most do to get the system where they want you pay around the same as a stock LM4/MKM. For what you get price wise it's still a great option, just something to keep in mind. I do find however that WE rifles work best using just a few upgrades to increase your accuracy and just replacing broken moving/contact parts as needed.

WA/WOC systems seem to have had little if any research and development put into them and have kind of fallen off as a wanted platform. Parts are still fairly available, but is slowly decreasing in availability as interest moves to other systems.

GHK is another brand that is supposed to be very promising in quality and performance. I unfortunately haven't handled it myself so I cannot attest to this, but I'm sure some gurus or people who have experience with them can pipe in. I would definitely keep this system in consideration.