Flexbox or Grid?
With the advent of CSS Grid Layout (Level 1) it's now a question - which tool should you reach for when designing components?
Some may say if it's a 1 dimensional layout use flex and if it's a 2 dimensional layout use grid. Other folks have written up flex/grid guides, and created multiple games around their use.
However there's no need for any more of that hard decision making. Enter a description of the problem you're trying to solve and this site will tell you the best answer.