(Osmo) Pocket Marvel!
For $599, this little gimbal-stabilised camera ticks almost all the boxes. It is small, shoots in 4K, and has a built in gimbal for buttery-smooth video. What more can you ask for? Sure, there are a few little quirks about this camera, namely:
Lack of availability of accessories
But, even considering these negatives, there are a whole lot of good things to say about this camera. With the recent firmware update, connecting to a smartphone is no longer necessary for use, unless you want to use it as a large viewfinder. In face, I only connect the phone when doing a firmware upgrade (I bought a USB-C to lightning cable because the included adapter doesn't fit with my phone case).
Video is amazing, and for a small camera with 2 built-in mics, the sound is pretty acceptable unless you're in the windiest of places. Battery life is OK, and whilst not replaceable, you can run it with an external battery pack.
I purchased a Controller Wheel for $99, and it is the best! It gives you MUCH better control of the camera's movements (I use it particular for vertical), but you won't be able to use the included case when you have this attachment on. I'm not sure that any of the other attachments are a must have, but YMMV.
All in all, I'm very happy with this purchase. I have made a short video talking about the gimbal of this camera, and have included a short time-lapse to show you just how well it works.