The next Doctor should be... the Great Catherine Tate--Donna Noble herself! Tate would be hilarious, touching, electric, and would:

1) Fulfill the "Doctor Donna" prophesy: What if the Ood foresaw not just Donna becoming the Doctor, but the Doctor becoming Donna? Her old human form couldn't handle it--but if the Doctor Donna was finally placed in her rightful Galifreyan body...

2) Continue the narrative of the Doctor choosing faces and personalities from his past, allowing the show to explore just how much the Doctor takes from his/her "donors."

3) Reignite fan excitement by harkening back to NuWho's most popular era: the Tennant years (though Capaldi is my fave NuWho:)

Sign something whimsical and positive. Bring back the Doctor Donna!!!