These past few years I have been a strong supporter of Asus's line of routers. They have proven to be reliable and performing, without the high cost that was always associated with some top quality brands such as Linksys (from back in the day). They cover the entry level with the RT-N10, all the way to high-end models such as the RT-AC66U.
You will find some information here related to Asuswrt, the unified firmware Asus has developped for their recent models. There is also information on Asuswrt-Merlin, the variant firmware I am developing for some of these routers.