Very interesting question I've asked myself a year ago. I ended up buying an old Netgear WNDR3800 for $15, and put OpenWRT on it. And it works great! It has enough ROM to install most of the services you would probably need need (ssh, iptables, smb, shadowsocks, dnsmasq, time machine, dyndns, are running altogether perfectly well) and enough RAM as well. OpenWRT itself isn't perfect, and I had to setup an package building environment on my machine to install some packages (typically shadowsocks) on the latest stable build (currently 15.05.1). But it works. And it works great. Speed is good, and I don't see anything I would have to complain about that disturb my needs/usage. I like the modularity and I love having a real Linux I can ssh to as router.

I've been quite interested to read about the fact developers from OpenWRT are moving to LEDE. Maybe it could be worth it to wait - as I said, OpenWRT isn't perfect and I'm sure a lot of improvements can be done. I haven't tried LEDE though. But I think, for a small office/home network, just getting an (reasonably)old/cheap yet powerful, compatible hardware and put OpenWRT on it is quite a good solution at the moment.