This is a Case Logic Backpack TBC411 for DSLR camera, there are a couple of good reviews of it on You tube.  The question is would the "Air" fit into it and it does, beautifully.  I don't know about everyone else, but I think the shoulder bag for the "Air" will do as a storage bag for bits and pieces, and that's it.  Having used the Spark shoulder bag on a number of trips and being able to fit everything in (including prop guards) it was such a huge disappointment getting the Mavic Air shoulder bag,  I have tangled up the shoulder strap every time I used it and the "Kangaroo pouch" for the prop guards is simply embarrasing.  After the huge design effort to put together the Spark, you can tell that DJI's design resources were maxed out and the shoulder bag was pretty much an afterthought.

Anyway, I picked this up on Amazon for £25 and its brill.  What makes it special is the "drawer" that drops out giving three storage pouches, one for batteries, one for the RC and one for the "Air".  There are side pockes for spare props and the prop guards fit nicely into the top pocket.  Its very neat, there is even a storage area for a tablet (up to 10") I believe.

Looks like a good bag.

I've got an EVOC Photop 16l, If you have a small mirrorless camera and MA, I would argue this is the perfect bag.

* Borrowed images from Google.



Front compartment for filters and other small bits



Camera compartment (3ltr) which is removable




Other side is left empty. You can put another 3ltr camera bag in, but I find the MA and controller fit perfectly.

Should probably say the EVOC is a bit more than £25

Sounds like you found one that suits all your needs.  Looks nice.
I've come to realize what is "Best" is entirely subjective.  What may be perfect for you may be only marginal to somebody else.  Who knows, six months from now, you may find a different bag that is even more perfect.

Very true, I used to think my Crumpler Cupcake Half Photo was the perfect bag, and very similar to the OPs. The problem I found with it was you have to set it down to get the kit out of it (fine for the MA but when I have my camera, the EVOC allows you to swing it around on the hip belt). Also found doing more adventurous walks it would move around too much.

Looks very nice but can't say if it's 'the best'