The long-running Doctor Who features a Time Lord called "The Doctor," who's over a thousand years old and has the ability to regenerate. And even though he travels with mortal companions, they too change after a season or three. But while The Doctor is still The Doctor, his companions are wholly new characters. They're a diverse lot of women (and sometimes men) who have little in common with each other except the desire to follow The Doctor through all of time and space, battling evil with logic, love, and varying adorable accents.

BBC

Oh, and they're usually hot, but not always.

Whovians love to argue over who are the best and worst companions, and for good reason. These are the audience's proxies. The Doctor is semi-immortal, more ingenious than any human, and filled with all the compassion and fury that comes from owning two hearts. We are not The Doctor. But we can relate to the humans he chooses as his friends and teammates in the fight against evil. That's why who you like most reveals more than your feelings on characterization and dramatic structure; it speaks to your own identity.