I prefer plastic nest boxes, if possible. Easier to sanitize and one less place for mites/poultry ticks to live. If you have a broody hen, the plastic can be rinsed, disinfected and dusted or sprayed with bug sprayed without worrying that there are seams that could be missed where mites could hang out and infect her or the little ones, since mites love to infest broodies while their whole immune system is depressed from all that sitting/lack of eating.
I also like movable boxes,unless your set-up requires the boxes to be in a certain place. Allows for training a confused pullet to lay in her box.