There's no option for what I prefer: natural NOT WOOD. Stone, ceramic, porcelain.
I like both wood and plastic as long as the handle shape/size looks good and feels comfortable.
Those aren't the only three handle materials out there...
Mostly out of practical reasons I voted synthetic handles. I love the look of wood but all the brushes that gave problems in the past had wooden handles. And when the synthetic material used is one of quality, like on the Vulfix and Simpson brushes, it is classy enough for me.