Boiled down to the simplest points.

You can get carbons lighter, for a faster projectile and they don't bend. However the they are either striaght or broke thing is not true. They can warp and lose spine over time. Sometimes they are not that great right of the box. If you want good carbons, don't be cheap and get the 50 dollar ones, you get what you pay for with carbons.

Aluminum are heavier and a bit more fragile, but they offer better quality control and consistancy for the price. Plus if you are worried about matching your spine perfectly there are waay more choices to choose from and I think they are easier to work with as far as tuning for length. Keep in mind that currently quality aluminums cost about as much good carbons do really. However I have never found you need to shoot expensive aluminums, the cheaper ones work just as well in my opinion. So if you are looking to save some money, you can get decent aluminums for less then you can get carbons with the same specs, they might just weigh more and you will need to be more careful with them.

In either case a good arrow spinner is a decent envestment if you shoot alot. It will let you know when your arrows are not up to snuff any more, and numbering your arrows doesn't hurt either.

Or you could get ACC's, the best of both worlds. However they are pretty expensive, but you for sure get what you pay for with them.

Good luck,
Paul