Depends on what you want.
I've always preferred dd-wrt (
http://www.dd-wrt.com/site/index) for my Linksys routers, it's also an open source firmware for those routers, more powerful and configurable than the original firmwares, but keeps the web interface. It is somewhat less flexible than openwrt but I didn't want another device I had to configure at the prompt
Then again, things may have changed since I last looked at this stuff. My current router+cable modem doesn't support any of the open firmwares