Personally, I like Sony's offering the most so far. Their approach to used games and online features are the main points for me, but the One is also only left with Halo as far as exclusive games that I must own go.
I'm leaning toward the PS4, but that doesn't mean anything because I'm not about to drop hundreds of dollars on a console with limited game availability. That's especially true considering the lack of backwards compatibility, plus I haven't had my PS3 for very long so I don't want to just put it on the back burner already. I'm not opposed to the Xbox One, but I'm still not sold on it as a whole. That said I see myself buying both eventually, but who knows when that will be.