Selle Anatomica. Looks somewhat ridiculous, is anything but lightweight, requires special treatment if used in rain or damp environments... but you can take it out of the box, put it on the bike, and immediately ride it for 100 miles with no discomfort. Because it is actually a saddle-- you sit in it, not on it. I've now logged 7,100 miles on my Titanico X. As comfortable as the day I mounted it to the bike. The only thing I could ever imagine replacing it with is another Titanico X.