What are the best photography apps on iOS, Windows and Android?

I really like VSCO - you should give it a try. :)

I've used a dozen different apps and VSCO has been the best.

I just started using Halide and it seems pretty great so far. I love the manual settings and the design is gorgeous. For someone getting into learning more about photography, it's a great way to learn more about concepts and settings in a practical way without dropping $1500 on a DSLR or mirrorless camera.

I believe it really depends on what are you looking for. There are a lot of types of photography apps, meaning, you can find apps to edit, photos, or take photos, or share photos. Even there are some apps where you share your best photos and if you are the "best photo of the day", you win some dollars. In this case, I'm recommending NoFilter. NoFilter (I'm a maker) is an app where you can find the best photo spots/locations around the world. So, for example, if you are going to go to Iceland, for vacations, you may have to check all the photo spots that are shared in Iceland in NoFilter, while you are planning your trip. You can even share the spots that you discovered. But, again, this is just one of hundreds of photography apps. We may even consider Instagram on this list.