Who would you're ideal siguiente companion be for the 12th Doctor? (It can be a anterior companion)

anterior companions that would be nice: Captain Jack, River, Vastra & Jenny. Maybe Psi & Saibra, o Shona. o K-9!!
New companions that would be nice: someone from a different planet, someone not necessarily female o in their 20's, someone NOT from modern día London, someone who isn't 'fiesty, flirty and sassy'.