I swear by Assos. I don't use it for rides under, say, an hour, but for those long Saturday morning rides, I wouldn't be without it.

On the other hand, I have no basis for comparison. I've never tried any other lube--Assos just happened to be the one my LBS had when I first went looking for a chamois lube, and that's what I've always used. Has anyone tried both Assos and others? I'm loathe to try anything else and be miserable for a couple of hours.