I think I've been lucky with respect to the pistols I have owned.
T68 pistol, never went wrong, reliable feed, simple.. oh so simple to maintain, never changed any o-rings, just a bit of oil. Brilliant.
SA-17 once I de-nerfed the co2 change, brilliant, good feed, heavy rain caused a leak, fixed by changing one oring, brilliant, but never really hit anyone with it...
T8.0 , bolt jammed forward on broken shell, caused by a fumbled mag change on the first time I used it. Cleaned, maintained never went wrong again.
And current T9.0 - no problems except a few barrel breaks, regulator works really well, I get silly consistency shot to shot over a big red, pretty much 0 variance up until the pressure drop, no seriously!, then it drops down by 3-10. When it jumps its between 3-5fps variance, when it jumps.....
It sounds like you have had bad luck, keep trying, you may get lucky!