I know how to flash firmware, but I'd still rather buy routers that have open-source firmware pre-flashed and tested by the vendor. This is simply because I've often run into issues with OpenWrt. I once bought a bunch of Archer C7s because it was described as a good router for OpenWrt, only to discover dmesg full of crashes from the proprietary wireless firmware running on the 5Ghz chip. In another case, I learned long after installing OpenWrt that the performance was much worse than stock firmware because OpenWrt didn't support hardware routing offload.