I'd like a new male character with a fair amount of screen time that says more than "Eeyup" and "Nope". They could just expand on Shining Armor a bit, but no one really cares about him.
Seriously though, I would like a new male character that interacts with the Mane 6 on a semi-regular basis. He wouldn't be a love interest to any of them, and would just be a non-close friend. He would also, of course, have character development, and be a strong, good character.
I, however, don't want to see him in the Mane 6, which I find to be fine as it is. I would also like him to be an "extended background character" of sorts, with speaking appearances at about the same rate Zecora or maybe the CMC have.
Probably won't happen like this, though.