Have you ever used a grid system, and if so, what do you prefer?

Before Flex became popular (around 2014), the float-based grid system was the most reliable because it still has the most browser support among the alternative existing systems (flex, grid). Bootstrap was using the float approach until Bootstrap 4 which switched to the flex-based approach.

Today, flex is the recommended approach for building grid systems and has decent browser support (99.64%).

For the adventurous, they can look into CSS Grid Layout, which uses the shiny new grid property. Grid is a two-dimensional grid-based layout system as compared to Flexbox, which is one-dimensional.