Thanks for the tips. That Zyxel router is going for $240 here in Sweden... which is more than I want to pay at this stage. I second hand Archer C7 might be around $65, I'll see if I can find one cheaper.
I cant recommend to replace a fully free working device with great ath9k wifi chipset that runs on fully free software with closed source ath10k crap.
If you need a really high end powered device, then get a used Netgear WNDR4700. The WNDR4700 is a high power SATA including USB-3.0 including 1Ghz CPU device with big flash and bit ram.
Note that the broad statement that the devices "require closed-source software to run", as I understand this poster's position, refers to firmware for the wireless chips, not the operating system in general.
While I understand the poster's personal position on this, I consider such a view extreme and in conflict with the reality that virtually all ASICs, CPUs, and microcontrollers on the market, including the ath9k that he claims to be "open source", contain firmware or code that is not "open source", whether that firmware can be downloaded to the device or not. Personally, I'd rather have a device where the firmware can be updated to resolve bugs, security flaws, or changes in protocols and standards, rather than frozen in silicon.
*) I realize that this is a bit short of the 200 required, so this might not be a real option, but if you set the wan interface to 100 Mbps ethernet you might get away without needing an upstream shaper and then you should have enough CPU for ingress shaping. But this edgerouter-x solution has no reserves for future bandwidth upgrades, so might not be the wisest decision ATM.