I kinda wish there was some way to make them talk while riding them, since they're capable of speech. Or if you place them down in your home. XP
I wanted that too at first, but then I realized that hearing the same lines over and over would get really old really fast, and I'd hate it after a while.
This is the biggest disappointment for me (which I acknowledge was more of a pipe dream than anything). I really wanted them to yell and complain when I made them jump off cliffs, or run into lava, or their butt got pepper with arrows because I dashed through a bandit camp. So much hilarious potential squandered!