I am obviously the baby of the forum, I was born during a Dr. Who, I think it was just towards the end of the Jon Pertwee time and the beginning of the Tom Baker.
Who I love? Well, Sylvestor McCoy. Sorry, peeps, but he was my childhood doctor and Ace was - well - Ace!
I don't remember any of the others as I have only seen one series of the old ones, and that I think was a Jon Pertwee time.
My memory of assistants are even vaguer, so I guess I have to say that so far, my favourite assistant is Rose. She was young, and there was great chemistry between her and the two Dr's she helped. Also, I happen to think that Billie Fox nee Piper (her other half is Lawerence Fox, part of the great acting Fox clan!), is a good actress. I like her! I could not stand Martha! She just made me yawn, in fact I kind of drifted away from her season, as I didn't like her. Then Donna Noble turned and sparked the show up again, which is odd, as I hate Catherine Tate as a comedienne.
But yes, my favourite Doctor is Sylvestor McCoy, and David Tennant. My favourite assistant is Rose, Ace, and Donna.
I do actually have the first of the Sarah Jane Adventures and they are pretty darn good imo. I think that once I get to see some of her as her assistant in old days I may form a better opinion but because the nasty bbc boss cut of Dr. Who then I can't say anything about any of the others and nasty BBC doesn't repeat them and I don't get sky and I can't afford the DVD's ... so frustrating!
So, I have to keep to my Sylvestor McCoy because he is the one of my childhood.