Its been a while since I was in Breck and Keystone but I would agree. Breckenridge has more of a "town" feel about it whereas Keystone village is rather ersatz in comparison (a similar comparison could be made between Aspen and Snowmass). There is a fair amount of ski-in, ski-out accomodation in Breckenridge too which is always a plus in my book.

Breckenridge and Keystone are a reasonable distance from DEN however the closest resort is Winter Park which is a firm favourite with the locals although I haven't been myself. Based upon your requirements I would strongly recommend Breckenridge.