I cannot help myself, I just cannot stop adding to this drivel. There are many aspects that need to be covered when judging a frame. Comfort, stiffness, dampening, Responsiveness, weight ext. Now each of these are important and tend to negate the other. To achieve the perfect balance you can "play" with a number of variables, such as build material (and mixes thereof), geometry, "butting" or reinforcing and molding of a frame, and componentry. A carbon frame can be built to be less comfortable than an alu frame, because responsiveness, weight and stiffness are more important (this is true of pro bikes). An alu bike with slack angles can be "Softer" than a carbon frame. However, as a rule carbon can acheive a better mix than alu anyday, however steel still seems to trump on comfort still. So when buying a bike one needs to first decide what you need and then buy the appropriate frame. For race snakes carbon is King, for recreation steel may be best, but Alu will be lighter and cheaper. For touring steel is the only option (personal opinion of course). To compare build material without being specific about the particular frame is really irrelevant. You need to say X frame vs Y frame, rather than carbon vs alu v steel vs titanium vs carbon/alu mix ext.
