there is nothing wrong with any material. it comes down to personal preference. right now the in thing is carbon. it absorbs roadshock, is light, is stiff, but it is also brittle, largely untried over time and cannot be repaired if something happens.

my brother rides one of the giant tcr's. definately a good bike. the others i havent tried, though i still have a raleigh trilite in my basement. i have no issues with feeling beat up or fatigued on an aluminum bike, so i ride one. i am a big guy and the cheaper carbons i can afford are typically pretty dead and lifeless. i like my bianchi nirone and would buy another in a blink.