The maker of the whistle is more important than the material. Two makers who make wonderful wooden whistles are these: Pat O'Riordan and Glenn Shultz (Thin Weasel Woodwinds). By going to the Chiff & Fipple web site and their page on high end whistles you will learn more of each. The O'Riordan's have a pure warm sound. Shultz makes whistles with a breathier sound: lovely in a different way. Other whistles are described and reviewed on the Chiff & Fipple.
Wooden whistles require more careful care. Avoid dry air and sudden temperature changes to prevent cracking. Periodic oiling with amond oil or light mineral oil is required. Swabbing dry after use is also required.
The Chiff & Fipple will give you links to web pages and email addresses for makers.