Wood is light and cheap so it is probably the best option. It is hard to break the handle unless you continually bend the shaft by force or squeeze your handle too hard.
i think victor puts carbon into some of the handles in their arterytec line i don't know what they're trying to accomplish though....
I think Gosen and some old ProKennex rackets have got carbon handles. But the outer covers are probably made by cork or soft rubber to absorb the vibrations.