I've had good service from Pro-Mags for a CZ-75B, a Beretta 96, and a S&W 669.
The springs seem to lose their life faster than Mec-Gars, and the plastic baseplates will likely wear out/break. (But Pro-Mag will replace them, free, without questions.)
I recently bought some EAA Witness mags made by Pro-Mag and they have metal base plates and seem quite good...
I think it depends on the model of gun you buy them for...