There's been talk of a "Photoshop killer" for ages, but nobody has managed to pull it off.
I think mostly because Photoshop is so many things to so many different people. If you're a photographer, you use and rely on certain features of the application while many others you just ignore or, more often than not, put up with because of the power of the features you do use. Same goes for graphic designers, web designers, illustrators, etc. And that's part of the "problem" with Photoshop. It's become bloated with features for everybody. Not to mention the subscription model.
Pixelmator was heading on the right direction at one point focusing primarily on photographers. Unfortunately it seems in the last couple of versions the new features have been for illustrators/designers or gimmicky Instagram-like filters. It’s an awesome piece of software, don’t get me wrong, but it doesn’t seem to be the ultimate photographer app (if there can be such a thing).
Acorn is also a great application. It’s just not focused on photographers either.
Affinity Photo seems to want to be that “Photoshop killer” (and I put that in quotes because just writing it makes me cringe, but you get the point). At least going by the video and what I’ve read so far, it looks promising. What’s encouraging is that Serif, the company behind it, already has a vector art and illustration software out there called Affinity Designer, so hopefully there’s no incentive to cram non-photography features into the new app.
I’m downloading the beta now and will give it a go.