K&M 18806

I ordered this as I move my midi keyboard (Native Instruments S88 Mk2) around in my room as it takes up too much space next to my computer as I also work there during the day as music is my hobby.

I love K&M products as they are solidly built and work well. This allows my existing stand to slot into it and wheel around with ease. It's well built and does the job perfectly. The only thing I'd say is that the 'feet' are quite big as accommodate two castor wheels per corner and you can bang your ankles off them if you're clumsy like me so be aware of that. There's enough space for most benches to fit under still without having to lift over the gap. And also a mechanism to clip the stand in place would be good in case you accidentally lift the stand out of the wheeled-base by accident which I do sometimes trying to lift the wheels over a cable on the floor for example. But otherwise I don't think you'll find better for this purpose unless you bought a stand with wheels already built in.