I'll though I tottaly agree I would just like to point out that Rose showed a dalek mercy, Donna Noble saved a family in pompeii, Amy forgave the doctor for taking her daughter away and Rory forgave the doctor for kissing is fiancee. so they were all very forgiving
I personally love Martha! I didn't like her at first because of the whole lovesick puppy look she had. Once she grew into her character she started being a badass XD
Martha Jones is my favourite companion because she saved the world by making people say one word which was doctor. She chose to leave the doctor because her family has been through one year of hell and she laughed at the master before he had the chance to kill her.