I used to prefer Christopher Eccleston, but I've really warmed to David Tennant and now he's my favourite Doctor. My sister swears she'll never speak to me again over this since she's a huge CE fan.
And I have to admit that personally I prefer Martha to Rose. I just like the fact that she's so clever. I've always preferred the clever companions. My absolute fave was Romana (her second regeneration above all). Not only could she hold her own against the Doctor, she seemed to spend most of her time correcting his mistakes.
Now if they could just figure out a way to bring Romana back I'd be very happy indeed! Hey, they brough the Master back so it
could happen!