If I could choose only one page builder to use for all my clients it would definitely be Elmentor. Elementor is a clean, pretty and free pagebuilder with a lot of customisation options. If you want a simple and clean website or if you want a highly customisable website then Elementor is the way to go!
Besides the fact that the appearance looks professional, it is very easy to customise your pages with Live Page Builder. Of all the free WordPress Page Builders that I use I never saw a better and more flexible editor than Elementor.