I would say that this was the most successful one I designed, measured by the criteria you mentioned:
It's small enough you can leave your phone in and use it normally without the combo becoming too unwieldly, and it's quite quick to install and...
3D printing might be one way to arrive at a solution.
Here's one adapter that's quite popular:
Here's one I designed for myself:
Mine is for digiscoping and only partially adjustable, but it's...