The sub model matters. Some manufacturers like TP-link change the hardware without updating model name. You can see the version number of hardware on the serial.
There's a crapton of routers supported. There's a supported device list and a bunch of Reddit/forum threads on the OpenWrt forums about best devices. The best device is the cheapest one you can get on eBay or clearance that works well with OpenWrt and can handle your network speed with SQM. Beware of devices with working OpenWrt but broken Wifi or broken 5ghz. This is by far the most common broken driver in otherwise working OpenWrt devices.
In general, MIPS and other weird architectures are the slowest, old ARM like v6 are faster, newer ARM pretty fast, and X86 is fastest. See list of SoC's https://openwrt.org/docs/techref/hardware/soc
Dual+ core variants of these architectures will handle more speed too. I would estimate single core MIPS is good for 15 megabits SQM, single core "old" ARM maybe 30. Newer ARM chips like Cortex 8, maybe 70 single core. For more cores just multiply those numbers.
Above ~300 megabits an x86 PC made with used parts will be cheapest. I have heard higher end Raspberry Pi are quite fast routers as well. For these options you will need a "dumb" AP for WiFi and just plug all the traffic through the wired shaping router with dual NIC's right between the modem and rest of your network. One NIC for LAN other for WAN side.
TLDR: If you don't want to fuck with anything, have $250, and don't have more than 200 megabits connection, get an R7800.
Other options can have things like crazy flashing process or broken stuff or unofficial builds or split AP/router or just take more research to find.
R7800 is wildly popular, well supported, fast-ish, has a lot of flash and ram, and somewhat easy to flash (you still to setup tftp on a Linux box to do it).
See my other comment about enabling per-ip fairness, it's an "advanced" option for piece of CAKE SQM script but it's easy to setup