I just downloaded Affinity Designer a few weeks ago to try it out and ended up making my wedding invites design in it almost immediately. It's great at picking up where Sketch leaves off, creating very dense, complicated vector designs.

I tried out Sketch very early on and gave up on it. Then in Oct 2013 I gave it another chance, and it's been my tool of choice ever since. I'd be very curious to know which flows you've fine-tuned in Photoshop to the point that Sketch would take more time. I had to use PS for a project recently and it was genuinely awful.