S3 is very memorable, I think. Strong atmosphere and some quite unique episodes. I haven't watched Sense8, but I looked it up because of Freema, and it sounds like something I'd like to try.

I love that Martha's smart, too! And she's got a lot of spirit and curiosity and just some special light that I can't describe. She's definitely the companion I identify the most with. Though I think Donna came down as my favourite (apart from Jack) on my first watch-through - curious to see if that changes or not. I love that she's so very different from what you'd expect the female lead of a prime time adventure show to be, and she still gets to be made of awesome and have that wonderful strong friendship with the Doctor.