In reply to Climbing Pieman:
Don't have Windows, but use Affinity on a Mac. It's a mighty good program, both relative to its price, and just in general. It works well with LR, where it can be set up as an external editor. Then you just have to right-click any image, select 'Edit externally' (or something to that effect) and the image is sent over to Affinity right away.
As for learning, Affinity a) has a great forum where questions are answered quickly, either by other users or staff, b) has a large selection of instructional videos on Vimeo and Youtube, that is continuously being expanded, and c) Serif (the company behind Affinity) is planning to release a workbook to go along with it, as they have already done for Designer.
Personally, I'm not editing crack, so I can't tell you whether it's exactly 100% as good as PS. From what I've heard, it's not (yet). But it's very close, and most photographers won't miss anything. Some things are actually done better than in PS, and Affinity also runs remarkably swiftly, even on my 4.5 years old MacBook.
Overall I really do recommend it.