maya is used in film/tv/games because it has the most accessable code for customizing. the interface is 100 times better than 3dsmax if you can script. the marking menus beat all other packages hands down as far as operations per second go. the main downside for most people is that 80% of the switches/controls/tools you need to use aren't readily seen in the main menu bar. 3dsmax on the other hand sticks everything and the kitchen sink on their attribute editor box, which leads to ridiculous amounts of scrolling.
max is the game developer default, mainly because the file/model format gives easy access to all the info(model/smoothing groups,textures,shaders) that game engines are typically coded to look for. that and the default character rigs have prepackaged/scripted biped,quadruped,etc. it was there at the beginning and most of the workforce is comfortable with it. maya and xsi are used by some developers, but most of the postings on creative heads is for max. valve is the main user of xsi.