I would like to get a boar brush. I use a badger but I like the idea of having a stiffer brush as well.
The trouble is I've not seen any with a large enough loft for my liking.
Also you have to find one where the tips haven't been cut to shape the brush because they will never break in.
After a few uses the ends will split up into much finer hairs making them soft to the touch.
These ones are mega money but bearing this in mind they could be the best of both worlds, the softness of badger but with stiffness too!