The chip inside the video card are all the same. The only difference is the cooling provided. Better cooling prevents thermal throttle and gives you better performance. But generally, the vast majority of cooling options for those cards are all the same. You just don't want a blower style card, which neither of those cards are.
The other difference is factory overclocks. The factory will automatically overclock the chip, but this is not worth paying extra for because you can get the same overclock yourself at home in about 20 minutes.
As for quality, they are all the same. Sometimes every vendor will have a defective part. I have never had a problem with PNY, MSI, EVGA, and ASUS. I have never had a Sapphire, but the are an AMD exclusive card maker, so I would think that they make good products or AMD would not have a close partnership with them.