I am presently using a WND3700v2 and it has run exceptionally well for the past few years. My place has quite a number of power outages and it hasnt affected it one bit.
At the moment i run openvpn client on my server behind the router. However, i would like to move that to the router. Can somebody recommend me a good router which fulfills the following criterion:
To handle power outages, you want a UPS. I have a similar x86 based self-built router it uses something like 10 watts idle, and a regular desktop UPS handles something like a couple hours of power outage.
Then, use wireless APs to add wireless to your network.
If you have a slow internet connection (say less than 10 or 20 Mbit) then you can saturate it even on OpenVPN with a more consumer level router.
I have WNDR3700v4 and I have OpenVPN server on it with 4 clients. I have installed mwan3 on it and packages to use 3g dongle. You can use this build it has included all these things except mwan3 if i am not mistaken Build for WNDR3700v1/v2 / WNDR3800
You can install mwan3 or buid your own version with it included. I think this router can handle what you want.
Personally I'd go for a PC running pfSense, its what I use here. I still have OpenVPN on my much beefier server though as its running 24/7 as a NAS anyway.
I only use LEDE for WiFi APs as WiFi alone tends to max out most consumer routers.