I shoot aluminums and carbons. For carbons I also like the Gold Tips. Like Redhawk says, you have to know your draw length and the weight you have your bow set up for.
Also, if you are going to use them to shoot into any 3-D animals (McKenzie etc) get the new tips for this purpose. Otherwise it will take 2 guys to pull out your arrows.
The nice thing about carbons is that they are a lot tougher and are either straight or broke. No straightening.
Long