Adobe (Lightroom, Photoshop) seems to be the standard all the others aspire to copy. For better or worse they went to a monthly subscription plan. Better because it brought a set of software down to an affordable level for the average photographer, worse because you pay for it every month - like the cable bill. For $9.99/mo you get Lightroom, Photoshop, Bridge, and some online storage, plus continuous updates.
Capture One Pro 12, is another one that nips at the heels of Adobe, in features. They offer both the perpetual licence at $299 or the monthly subscription for $20/mo.
Adobe Photoshop Elements is a stripped down version of Photoshop, that sells for $99.99 for a perpetual licence. It handles most all but the advanced editing.
Coral Paintshop 2019 Ultimate, has a Ps feel to it and many features that mimic Ps. It sells for $49.99 for a perpetual licence. I've used this one before and found it to be very advanced. However it had a problem with stability that would cause it to crash unexpectedly. Not sure if that's been fixed yet.
Have no experience with Affinity but there are a few on here that seem to like it. It also sells for $49.99 for a perpetual licence.
As mentioned Gimp is an open source free software. I've heard it's a little difficult to learn, but have no experience, and the manufactures all have free basic software.
One of the values of Adobe are all the 3rd party plugins, presets, profiles, actions and learning videos. Makes the learning a lot easier.