I've had excellent success with QCA and Broadcom. That said, playing with a QCA AC2350 MU:MIMO chipset now (at least, I think it is QCA. I haven't taken the thing apart to check) and the 2.4GHz implementation seems to be having performance problems. I am only hitting 11.5MB/sec 2.4GHz 20MHz and 24MB/sec 40MHz on downlink. Uplink is just fine and the 5GHz band is very good on uplink and downlink (these are all 2:2 to an Intel 7260ac and close range. Medium/long range performance is pretty comparable on both bands and up/down).
By comparison, I have a C5 and C8 TP-Link Archer and I have tested an 11ac Netgear or two and all can hit around 13.5MB/sec or so on 2.4GHz 20MHz and about 28MB/sec 40MHz operation. So the fact that the router/chipset is hitting roughly 20% less is troubling/odd, but I haven't heard much from the manufacturer about what might be up.