I'm no expert but have a couple of remarks... I see pros and cons to the terra cotta and plastic used for any plants.
Unglazed terra cotta is porous and I imagine that the soil would dry out faster. Plastic would retain water longer. Terra cotta is heaver and thus harder to move around if you have lots of them and want to rotate or move your pots. Terra cotta has that certain look that plastic doesn't but plastic is lighter to move around and doesn't break when tipped over (which I find happens a lot to some cacti as they reach some height and top heaviness). There's always the nice aesthetics with pots that all match somewhat in material...
I think depending on the collector's preferences and priorities, the choice would be dictated by those factors.
