For stability and height adjustment options, I recommend the KUN Shoulder Rest to all my students. I use it myself as well. Here’s a picture of it:
I have tried the playonair, which is a sort of blow up cushion, but it’s very low. I have looked at the Bon Musica but I haven’t tried it. I notice it is generally 3 times more pricey than the KUN Shoulder Rest. It sort of looks like a ‘contraption’ lol. But if others have tried and used it with success, perhaps you will too.