Long term, PS4 is almost certainly the best idea. Just look at the number of exclusive games that M$ have released in the last 2 years compared to Sony, I have bought just 1 Xbox 360 game released this year (Gears of War Judgement).
Microsoft had lots of exclusive games for the first few years last generation and then it definitely faded away, their initial early investment has to count for something long term, so they can't keep throwing around $50m to get timed exclusives
Anyway, it doesn't really matter, most of your gaming time is going to be spent playing cross-platform games. The best game of this year is clearly going to be GTA V (Watch_Dogs is the only next-gen contender) and we have absolutely no idea what games are coming next year
All I know, is that Sony have more quality games studios than M$ and with the oh so very exciting confirmation that Naughty Dog, SCE Santa Monica and Media Molecule are not in fact twiddling their thumbs and are indeed working on PS4 games, the PS4 seems to have a better pipeline of games coming.
But that's just my rational behind buying a PS4. I explained this to my friend and he responded "but Halo." So each to their own