Authored Comments

I have used both Bootstrap and boilerplate quite extensively but, for green field projects usually find myself using ZURB Foundation instead.
It is equivalent to Bootstrap (which is great, don't get me wrong) in terms of scope but (in my opinion) you end up creating much cleaner code and the way it can be customised through SASS allows you to create a style framework that has just what you need in the way you want it.

In my above comment, I forgot to mention that it also has a bunch of ready to go code in the form of both templates and building blocks. You should check it out!