Its nice to see that Donna gets so much love! I was under the impression that people didn't like her. But I totally agree that she was the one that changed the most and was probably the most fun.
I'm one of those people that actually likes Martha. I agree that she was seriously undermined by the writers having her pine over the Doctor. On the other hand, she was most competent of all of the new companions and the most useful. Hell she went all super spy world traveler in the Master's alternate history. It made sense that she, of all of the companions, would end up working for UNIT and being a consultant to Torchwood.