Sony, price, and MS's colossal misfire on the Xbone original plan.
It's the cheapest next gen console not counting Wii U, so that gets a lot of people interested. But I think one of the bigger advantages is the slew of bad press around MS when they revealed the Xbone. I had a PT retail job on the side this holiday season for some extra cash plus discounts and it was amazing to me how many people still thought at launch that the Xbone would not play used games and required a 24/7 broadband Internet connection and you'd never be able to rent, loan out, or borrow games. I think this lead to tons of people shying away from the Xbox brand.
All that aside, I listed Sony because they are still of course a big force in the industry.







