For me, I would buy carbon. The price has come way down and the smoother ride is a plus. That being said, I have had plenty of great aluminum rides. And still use one as a rain/travel bike. Like the other post says, fit is the most important thing. You can be on the hottest carbon rig yet have all sorts of issues due to bad fit. I would think that the main barrier for a first bike being carbon would be the price. But if money's not an issue I would get the carbon. And there are good carbon bikes in the $2500 range now.