Most of those run OpenWrt or PfSense. Assuming the hardware is well-supported by the open source software it runs, there's a argument to be made that there's no difference. There's always the risk of them using some weird chipset that won't be supported in a year's time. The only difference is that the OpenWrt One is specifically designed for OpenWrt with well-supported hardware.
how good is openwrt these days? i used it a long time ago on tp link hardware are remember it was not too good...like adding own scripts, addons etc. and then i tried stuff like ipfire,ipcop and pfsense. pfsense was so much better and now opensense is quite good.
how does current openwrt compare?
OPNsense is like comparing a bicycle to a car (in Europe)
Both will get you there,the first one is more convenient most of the time for most users,but the second one is a whole class of "more powerful".
But it's far easier to take a shortcut with a bike.
Whilst that's a nice slogan, in Electronics "open source" doesn't mean anywhere as much as it does in Software because it's generally just knowing which components go into the circuit, which is but a fraction of the work (laying out the board is a massive chunk of work, in some cases most of it, and at high enough clock speeds circuit design is an art in itself).
Mind you, I like the Orange Pi and Banana Pi guys, and the idea of an SBC designed for being an open source router is pretty appealing, though nowadays maybe pfSense would be a better choice than OpenWrt.
Finally this thing having only 2 ethernet ports + WiFi makes it little more than a regular $70+ SBC board + a box - something easy enough to put together by any technically inclined person - which isn't exactly exciting.
The very example I provided comes with an mPCI-e slot to install a WiFi card of your choosing.
Also they have SIM card slots so you can install a data SIM card and set-up a fallback configuration that switches to it if your landline internet connection goes down.
Yeah, the case with antennas is a good point - when I decided to concentrate various things in a Mini-PC in my living room (TV-Box, Router and so on) I actually looked into these router Mini-PCs as an option and the biggest problem was the lack of a proper antenna, so I ended up going with a generic Mini-PC and leaving out the router functionality which remains done by my old router (which is quite decent, just a bit outdated).
Mind you, this one also wouldn't work for me because I'm using 4 Ethernet ports (1 for the external connection and 3 internally) whilst this one only has 2 (a weird choice for a router).
IMHO, this isn't really better than just getting an SBC with 2 Ethernet ports and WiFi and put it in a box with an antenna), a setup which suffers from exactly the same problem as this one: not enough Ethernet ports.