The revival-era show soft-reboots every time there's a new Doctor, to intentionally make it a good spot for new viewers to jump on; the basics are all subtly reintroduced as the story progresses. If you find yourself intrigued by one Doctor or another, you can just start with that Doctor's first episode. (Not the one in which the regeneration happens and the new Doctor is introduced at the end, but the one following that in which they're the Doctor as it starts.)