I keep hearing about how great KEE's customer service is, but all I know firsthand is that I sent them my SA17, they held onto it for 2 months without updating me unless I chased them down, lied to me about why it was taking so long (claimed no parts, when really they were holding it to put the recall parts on that I DIDN'T ask for, sent it in just before the recall was announced), then sent it back still leaking from the pierce seal.
To their credit, they did sent a free spare parts kit as well as a Rifle Kit upgrade to me free of charge for the inconvenience, but due to my confidence in their reliability being destroyed, that was the last KEE gun I bought and will continue to be so.
While I may be biased, GOG has excellent customer service and has always gotten replacement parts to me in a timely fashion when I needed them. They've also taken great care of my team as a sponsor. I've also never heard any complaints about Eclipse CS, so I would be confident doing business with them as well.