I like how easy it is to use with AngularJS, but also that there are so many plugins available out of box! It's almost too much choice sometimes - you're bound be overwhelmed by all these choices :) Also we have problems integrating select boxes from other applications into our site when using angularjs as frontend framework since they don't follow standard conventions about what should happen if an option isn´t selected anymore or not yet chosen etc., which makes them difficult/impossible without rewriting some code each time new solutions become more popular than old ones ;).