Price-at launch it was $200 cheaper than PS3, and for the last 5 years has had a $199 model whereas PS3 has yet to reach that.
Xbox Live-even though its the only online service that costs, its considered the best and worth the price.
Exclusives-Halo/Gears/Forza/Fable are all critically aclaimed series
Multiplats-not true anymore but for awhile it had the best version of most 3rd party games.
Controller-the most comfortable controller on the market
Im not an Xbox gamer and dont own a 360, these are just some of the things ive seen/heard as reasons people prefer 360.
When the herd loses its way, the shepard must kill the bull that leads them astray.