To play devils advocate, Microsoft has more studios than Sony now... And a massive portion of which we haven't seen make an exclusive that really pushes the Xbox's hardware.
Actually, at last count, they were about even (around 15 each). This is particularly better for Sony [currently], given their 1st Party studios put out more hardware pushing content.
Of course, I expect things to even back out some at the beginning of next gen, but I just wanted to clear up that little misconception. :P