I disagree, to be honest. I think Jamie is simply more of an extrovert. He's certainly not more likable, based on what I know. He's slagged off Andy quite a few times and dumped Eric Butorac just as he thought his career was about to take off. Andy is a much nicer bloke. He just isn't all smiles on court. Then again, how many players are?
Oh Clydey I do like Andy, I think with him what you see is what you get, he's not one of these people who is completely different when the cameras are on to when the cameras are off. Personally, I like that. There is nothing fake or sugary about him.
Maybe Jamie is just is a bit more savvy when it comes to playing the media and public persona game as I think lots of people think he is the "nice" one. He just comes across as more personable in interviews imho.