The thread on "Favorite cheap" linked above is a good starting point. I broke down and bought a GL.iNet "Slate" (~US$70, dual-band, travel-sized) a couple of weeks ago, but haven't unwrapped it yet, so can't comment further. I purchased it for its dual-band capability, size and ability to run off 5 VDC, not its CPU power. From the OpenWrt mailing list, last night, Alberto Bursi wrote;
On 05/12/2018 15:08, Carlos Ferreira wrote:
I still have a bunch of Old Foneras and some TP-Link 703N and TL-MR11U
battery powered micro-routers.
The foneras are kinda useless, but the TP-Links are somewhat usefull
and I still use them with OpenWRT.
What other inexpensive routers would you sugest to substitute the ones
from TP-Link I just cited?
I'll recommend GL.inet minirouters, AR150 (which is basically the same SoC but with 16MB flash and 64MB ram) or MT300N, AR300M lite. Can be found for 20$ or less and are all straight upgrades over the 703N while keeping the same size, more ram/rom/ethernet ports, SD card slots and PoE modules in some cases.
Their battery-powered minirouter has a mini pcie slot for a 4G modem, but it's not inexpensive. It's around 60$ without the modem (or more with a 4G modem installed) It's the GL-MiFi.
They use OpenWrt as base firmware, and have web interface in uboot for firmware recovery.
That all said, if I wasn't looking for size, I'd definitely go with a ARM-based router if looking for an all-in-one. I personally run my routing on x86_64 / AMD64 devices.