It makes no difference, really....do you want lighter and faster or heavier and slower? Technology has advanced enough on carbon arrows that tolerances are becoming very tight...But the downside to that is they are a bit more expensive than less tolerant carbons..but well worth the money.

Personally, I don't shoot aluminum because when you bang them together, they get all kinds of dents and dings which effects their straightness. BUT, it's possible to break the spine in a carbon arrow doing the same.....So...like I began with, it really makes no difference.