There are many models of routers that support open source router software/firmware like OpenWRT, DD-WRT and Tomato. However, when you look around, it's very difficult to determine the recency of router models out there and post date isn't always useful since many use which ever router just happens to be available to them for free. If one were to decide to buy a brand new model router to install open source router software on, where would you go to find out the best current models and be able to compare their features?
While it would be nice to know the best models as of today (December 1st 2013), I think it's more interesting to be taught how to fish instead of being given a fish. This also makes it easier for me (and anyone else) to pass this advice onto the next person.
I'm running Merlin's AsusWrt on an RT-AC66U and I've been very happy with it. I bought it earlier this year to replace my aging WRT54GL which had run with Tomato for years.
I'm also a fan of OpenWrt, but I use the x86 build on a VM host, it acts as a router/firewall to other VMs in a private bridge.