The Banana Pi is easy to get going, simply download the image and flash on a SD card. We’re talking about a vendor that actively supports OpenWrt after all.
There are other devices supported by OpenWrt and this might interest you. Checkout the tables. There are also tons of Commercial routers / AP that are supported by OpenWrt and will provide a good experience but you’ve to pick them very carefully.
About range its mostly the WiFi chip manufacturer and if you want open software or not. It boils down to: the devices with the most range and speed are usually powered by Broadcom (Ubiquiti and whatnot) but you don’t have OpenWrt for those chips because they don’t provide open-source drives. MediaTek and Atheros are very open-source friendly and they perform well but Broadcom is Broadcom.
I’ve been running OpenWrt and DD-WRT (supports older routers some with Broadcom chips) for about a decade now and I don’t see me going back to bullshit vendors and their cloud stuff. I even deploy those on customers (usually small offices 10-50 people) and they’re happy with them as well. The Banana Pi BPI-R3 is my main router / AP and I’m very happy with it, more CPU and RAM than required for sure. I also deployed one at a customer and it runs flawlessly. Whenever the R4 is released I’ll deploy one to another customer who’s currently running a bit short as their current router is having trouble with more than 10 or 15 VPN clients connected at the same time.