I wasnt going to post here as everyone knows I hate Xbox systems. But I will give the main reason why and its simple : I have 3 broken xbox/360 systems in my house and no broken playstation systems.
It must come down to personal experience. I have a pre HDMI 360 that I bought used that is still running strong. I just clean it of dust periodically. But I have had experience with 3 PS2s and all were horrible. One had faulty control ports, one had difficulty moving the laser. and one that someone I know has to play it upside down now. I always considered the PSX fairly rock solid. But after that the build quality was not the same. But I assume that is just the limited experience I have had with them.
But my dislike of Sony goes more toward the use of proprietary standards, advertising an open linux friendly system and taking it away, advertising backwards compatibility and taking it away, and so on, they are a very bait and switch company. I won't even mention the entertainment/music side of the company.
The XBox is just a PC. If anything goes wrong, it can be fixed easily. They released development tools, and the XBox has one of the best most lively mod scenes because of that. I think that is what I like about them.