Personally, I’m most excited to meet Fifteen. Every promo pic of him makes him look cooler than the one before. (If absolutely nothing else, he has fantastic fashion sense-- guess the reason all the other Doctors were so fashion-oblivious was because he was hogging it all for himself, lol.)
I’m most looking forward to RTD’s writing. I really connect with how he wrote his characters in the first four seasons and I’m really excited to see the new ideas he’s got in store.