I like having quick access to the bits I most commonly use. I've used rubber bit holders and they seem either really tough to get out or too soft. I've also used designs that retain the bit with a magnet, these have the potential to collect metal fines, and it's also another component to source. I designed one version that uses magnets on the back so it can attach to a metal surface. I used this design for over a year in my previous carpentry role, and learned how the design could be improved when it would break. The leaf spring retention design has been incredibly consistent and has not shown signs of wear or loosing it's engagement.  
Testing and failures