If you want one of the big 3 to go the way of Sega, or want your preferred company to monopolize...

[scottie]

Improve? i.e. the objective term? None of them.

In terms of my personal enjoyment I would be happier with MS out of the picture. They are 1 of 2 companies suppressing the style of FPS that I enjoy, and they are also leading the charge against local multiplayer.