Yeah, thats the obvious one, isn't it!
Theres also the other (purely gaming) factors:
-larger game library
-cheaper games
-ease of mods, patches, etc. etc.
-Possibility of better performance
At the end of the day, if you don't know why you are spending 2x-4x as much for a PC over a console, then don't buy a PC!
It must be very rare for someone to want a PC solely for gaming. Everyone needs Email, word processing, work programmes, connectivity, file storage etc. etc.