Here are a few I like:
padauk, sycamore, African mahogany, bubinga
Padauk is #1 for me, but with all of them, it also comes down to the striker dimensions. I can make a sycamore striker than runs as well as any other on aluminum, and I can also make one that isn't even worth saving for the fireplace. Also depends on how you hold it too. I have had good luck with diamondwood strikers for aluminum, but I have to make them real thin.