Actually Ive had good FEJ models and bad ones, but I can conclude they are crap.
I've had good SM kits and bad ones as well....but in my experience unless you get the latest and greatest, they too tend to get crappy with time.
My last two SM F-16 I spent days cleaning the inside fuselage, getting dirt and resin residue out. Bad fit of gear doors, poor inner gear lining, big pockets of glue everywhere, heavy paint jobs and same Chinese pine wood everywhere. To their defense the gear is flawless, but now I read that others are not that lucky with the air cylinders. My SM cylinders have always leaked buy never to a point where it bothered me.
Anyway, I'd still buy SM, but not FEJ. And I will now stop so I don't get blacklisted. :-)