When I print out music — although I buy plenty of published books of sheet music, too — I print it on card stock, which is a lot heavier than ordinary paper.
It doesn’t flop around when just propped on the music desk, and in a 3-ring binder, it still turns easily. For the latter situation, I attach a small colored tab on the edge of each page, so it’s super easy to grab that and flip.
I’ve used digital music on my iPad occasionally, but I find that turning pages there is a skill with a significant learning curve and I haven’t found the time to devote to that. Not yet, at least.