As we can see, both ways can be viable depending on our specific scenario; therefore, the decision between going with a custom grid and adopting a framework-based one should be made on a case-by-case basis.
That said, after our non-exhaustive analysis, we think that adopting a frontend framework might be a good call for our project; we'll also keep Bootstrap for the task, since it happens to be one of the most suited ones for native web applications based on Angular, as we'll be able to see in the following paragraphs.
It's worth noting that by choosing Bootstrap, we're ditching a great alternative that will surely pave its way in the upcoming months; we're talking about material2, also known as Angular Material, a top-notch component library based upon material design. The only reason we didn't pick it is that the project is still in beta in Q3 2017. Whoever is bold enough to try that can ditch this chapter entirely and step into that pair of shoes by looking at the official project page at https://material.angular.io/ or look at their source code repository on GitHub, at https://github.com/angular/material2.