[baby]

I've been using both of them a lot lately. I'll give you some answers:

Bootstrap is more like a theme to me, if you don't want to bother buying one and you don't mind having a "bootstrap" look go for it. I love doing quick mockup with it. But as soon as you have to design something, it's a trap, it makes you lazy and want to use their styles for everything.

Foundation has a better reset in my opinion (I like box-sizing:border-box). The rows act like a container (size depending of your configs) whereas you can play with row and row-fluid in bootstrap (which might not be a good idea on a project). Also Compass + Sass. Forms look better. Orbit looks better than Carousel...

These past weeks I've been using both since I can't really make up my mind on one. I'm going to dig into Foundation 4 to see if it's going to change the situation.

EDIT : I'm looking at it right now, it does look pretty awesome. It seems they're taking a very different direction from bootstrap: - you now have to stylize elements through CSS (or SCSS) like it's supposed to be! They provide a long list of example, it seems like their stuff is entirely and easily customizable (which was always the shortcoming of Bootstrap). - I taught a friend who didn't know HTML nor CSS how to make websites a few day ago. I taught him Bootstrap. He's loving it since then. Looking through Foundation 4 the idea that it would be way too difficult to teach him Foundation 4 has stroke me.