Traditionally Maya has been the weapon of choice of high end broadcast and film vfx professionals (up there with Softimage), and was priced accordingly until recent times when Alias slashed prices, even releasing their Personal Learning Edition for free. Max had been considerably cheaper until then and had excellent tools for creating lower end and real-time assets. The two platforms have been converging on each other, with max 6 shipping with the MentalRay renderer as standard and Mayas improvements in lower end tools.
Its very much a pricing and personal preference when it comes to “which is better”, with a lot of artists tending to stick with whatever app they learned in college.
Its max all the way for me!!:D