My best-riding bikes are steel. My '97 Trek 750 is my newest steel bike. My '70 Peugeot is my oldest steel bike. The ride quality of both is sublime. My "do it all" bike is a modern MTB that I've sort of "hybridized", and I need big tires to keep the ride quality reasonable.
One of these days, I'm going to buy a new steel disc frame and move my MTB/hybrid parts over to it and have a fully steel fleet (at least for the bikes that I ride -- my family still has other aluminum bikes).