I have several MFJ products. The only issues I have had with them is on two antenna tuners, the knobs were slightly out of alignment with the capacitor vanes and needed to be adjusted, and the SO239s on them are VERY excessively tight on the center conductor of the cables. On a third tuner and on my Antenna analyzer the connectors have a typical, normal mount of tension. And one of the tuners needed to have a nut tightened on a rotary switch shaft.
But otherwise they have all been reasonably priced, useful bits of equipment. I like their manual antenna tuners. I have a loop tuner that is a lot of fun to experiment with. The analyzer is about as nice as you can expect without a graphic display. I have read of complaints about the soldering work inside but on all of the ones I've opened up, they appear to be in good condition. Maybe I just got lucky.
I really don't mind doing piddly little tune-ups on their equipment because the overall value for the dollar is pretty good. In my experience nothing has been broken so much as in need of very minor fine tuning and adjustments. All of the stuff would have functioned fine without the adjustments, but wanting things to be as close to perfect as possible, I couldn't stop myself from "fixing" them.