When I decided to Jump from building PC's to something more convenient I went for XBOX over a PS3. I think this was largely down to some price cut / bundles at the time and the PS3 was still quite a bit more.
I have sometimes looked at also getting a PS3 so I can play Uncharted etc. but There have not been many other games that have justified the extra expenditure so I stick with what I have as many big games are cross platform.
I guess what I am saying is that if you turn that argument around you have to think what you would gain ( really gain ) from buying an Xbox. I wandered past a 3DS display in the local Asda the other day and thought ooooh that would be nice and new and shiny but I have an IPhone and IPad so That satisfies most of my portable gaming needs. Of course I don't get to play the Mario's and Zelda's but I also don't have to fork out the cash for the console and the games.
it's always good to have a new shiny in the house but at the end of the day it's what we use them for that we really get them for. I have an Xbox for games. It's a games machine. It used to be a PS2 a PS1 a spectrum and so on.
So what would I do? If I had the money I would have the lot. All the consoles a big F**K off PC rig. But I don't so I make choices / sacrifices to maximize my gaming experience.
If you feel that the outlay would justify the experience you get then go for it, ( but maybe take the middle road and get one on the cheap so you have a bit of cash left over for all the games and you Xbox gold membership)