A suitable responsive framework for WP theming?

Hi there, I have built many themes using bootstrap. One of these is actually part of your official directory of themes. https://www.ads-software.com/themes/iamsocial/ Now, I have to code a theme for a big publisher. I want to make sure the theme I will build for them lasts in time and is easy to update and maintain.
I am trying to find out if Bootstrap is actually a good option. Any thoughts? Any other responsive framework you would recommend? I have used Foundation sometimes. Just got more used to Bootstrap syntax.

I am just willing to hear opinions…. Let me know. Thanks.