The Mt. Shasta super century in Northern California has (according to the website) a bit more mileage and a bit more elevation gain. Having done neither I can't say which one is really more challenging, has better support or is more scenic.

The Death Ride has been around longer, and has gotten a lot more attention -- with a name like that how couldn't it?

However the Mt. Shasta century has a 750 rider cap, which is a definite plus.

Maybe I'll try for both next year. yeah, right.