Reliability is going to be a wash if you do routine maintenance. The Etha is slightly fewer orings if I remember correctly to do routine maintenance on, so it will, in theory, be a little easier. But neither is truly more reliable.
Better overall is totally opinion, and I would choose the Marq. For the price, I'm not a fan of how the Etha feels in the hand, how it shoots, or how the trigger feels. Marq definitely has a craptastic stock trigger IMO, but it shoots quite nicely, will be more efficient (significantly more if it's got supercharged engine), and feels better in my hands.
Etha's going to be lighter if it matters.