Looking back, I actually can't think of another reason why I chose Bootstrap over Foundation.
If I'm a non-technical person with minimal coding skills (C++, editing HTML/CSS, rudimentary knowledge of Ruby), should I invest time and effort to learn Bootstrap/Foundation? My goal is to develop a functional MVP that I can take to potential customers; I've validated the need for my product through individual sales but feel like I need to test a semi-functioning site to see if my idea can scale.
http://html5boilerplate.com/ is a great choice not yet mentioned. More of a blank slate though so you will need to do some design work. It is responsive in nature which makes formatting for mobile devices easier too.
I like Skeleton the best of all the recommendations I've seen thus far, and use it in most of my recent projects.
Skeleton, unlike all the other things I've seen mentioned, has almost no overhead, and pretty much stays out of your way. It's got sensible defaults, isn't as recognizable as bootstrap, and doesn't have any cruft.
The biggest knock on it is that it doesn't have enough widgets, but I for one don't want them. I just want a responsive grid framework that looks decent out of the box. If you're like-minded, Skeleton is a treasure.