cyma non blowback AKs would get my vote for being super reliable workhorses. I've serviced the AKs at a local rental field and after a couple years of weekly use, 3 of 20 or so needed new nozzles... 1 had a motor seize. You're talking about guns that are seeing probably 50-60k rounds a year with only 3 nozzle failures and 1 motor issue. No stripped pistons, no broken gears, nothing.
Given that they're rentals and it's hard to say what happened with the motor failure, it could have been abuse or the motor shed a winding... which can happen to any motor. The guns are dropped, thrown in the dirt, played hard in the rain, I don't think you could ask more out of a 200$ gun.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.