I'd consider going with the most powerful console available as my console of choice for multiplats and online purchases. (I'll probably get both the next PlayStation and Xbox.)
However, this generation has shown me a few things which would make me inclined to stick with Sony. The following is obviously my opinion:
-Sony are the most willing to experiment and try their hand with new IP's. We're still getting them 6 years after launch from top quality developers. New IP's are far more interesting than X installment in an established franchise.
-Online service is free. I do not want any more subscriptions on top of Netflix. Even if it isn't a huge amount. I spent years paying for WoW and Live, I'm not going back to that unless I'm forced to.
-Sony are willing to push the hardware. Even if they don't release the most powerful hardware on the market, they have some great studios behind them who have produced some of the most dazzling games this gen. I'd really have no fear that next gen, even if they come up short on the hardware, ND, Guerrilla and SSM will still pump out beautiful looking games.
I feel MS haven't really been on par with Sony in these areas this generation. If next gen it's more of the same, I'm not jumping ship even if MS push a billion more pixels. That's the beauty of a new gen though, so much can change and as I said already, I'll probably end up getting both.
