9 was my first (I haven't watched any of the original series) and I was so devastated when he regenerated into 10, until 10 woke up and was amazing!
Since then it's all about 10 and just how amazing he was. I loved him most with Donna and I'm glad so many other people like that pairing, many people I know always think Rose was best because 'Billie Piper was hot'...
I loved that Donna didn't love the Doctor, romantically anyway and they got to be friends. Lots of my favourite episodes are in their time together, especially the library and River.
So, River is the other one I wish there had been more time for her and 10 because they were excellent together in the time they had.
I really can't get on board with Clara. I was super excited when I found out she'd be the new companion after the Dalek Asylum but then what they did with her story and she became a 'modern english girl' it just made me sad. I was hoping she'd be from the time in the christmas episode.
Hopefully she's different with 12.