I always loved Tomato; ran it on my 54GLs which I still have (though one is pre-L branding).

I had a Cisco E3000 that I tried to love; bought it because it supported DD-WRT so once I got sick of the Cisco firmware I tried DD-WRT. It seemed like an endless headache and never worked quite right, so I flashed back to the stock Cisco stuff; I realized the stock OS supported everything I needed anyway, and was more stable. I wish consumer stuff had more cool graphs and the like.