In my quest to dump Adobe tried many but found that I still need Photoshop (and unfortunately, now inDesign requiring the full CC) for that one feature I need and others can't do. The big one is working in layers involving multiple photographs. Most refer to layers as a tonal adjustment layer of the same photo. Having tried...and using for specific features...following summary, in order.
1. Affinity Photo. Very full featured and excels in one feature - in addition to being the least expensive @$49, doesn't mine its customer base with annual upgrades usually around $100 which is the same as simply subscribing to Photoshop/Lightroom. By their policy, only upgrade will be wen they go a full model number from the current v1 to v2 and every decimal upgrades, currently v1.7 I think, is free. The other weird thing about Affinity is that they use non-standard terminology that have to get use to.
2. Luminar 4. Good with limitations but nothing better on sky replacement. I have found though that the sky will introduce a pale blue/cloud mask impacting other areas (white eaves of house, etc) and now use it as a plug-in in Photoshop and make a duplicate layer that can later bring in to paint back with low opacity impacted areas.
3. On1 - This probably ties with Affinity Photo as Luminar is special use as primary feature. On1 one is relatively full feature and give you an option over Lightroom - don't have to import into catalog (which it also offers) and can work on photos where they are on the hard drive, not throwing a fit if you move or re-name them.
4. Capture 1 - borderline useless. "Free" version is very limited so immediate upgrade to full (camera specific or very expensive universal). I had/have the Sony version originally paid $49. Not only do they have annual upgrades but annual price increases for the upgrade where I think it is now $125. Hasn't had the cataloging feature (didn't check to see if added) so work individually like in Photoshop without Lightroom. Fuji/Sony sounds good at the low price until reality hits and you realize need the expensive full version. Reality - Unless Fuji/Sony is your first camera, you probably have a hard drive full of Canon, Nikon, iPhone or other photos that it will not touch. Likewise in the future wanting to touch up an iPhone photo, downloading a stock photo or something a friend emailed as an attachment, or even scanning a physical photo/document to a jpg. It is not Fuji/Sony.
5. Adobe Photoshop Elements - I haven't used it but know people who have. It is actually a very good program, and given the history, more feature rich than Adobe wanted but competition pushed. Adobe needed something in the $99 pricepoint to compete with Photoshop's main competitor, Paintshop Pro, but had to walk a tightrope an not scavenge their Photoshop customers with it being too good. I had Paintshop since it was one of the original 4 "must have" shareware programs. Developed a year or two after Photoshop and marketed as doing 97% of what Photoshop would do. Still does. Owned it as it made the jump to a commercial program, first JASC and now Corel, adding the "Pro" to the name. While it is feature rich, Corel has "improved" it downgrading the interface to make it look toyish. Biggest problem after all these decades - PC only, no Mac version...and while I have Parallels, I refuse to use it under that program as Corel suggests. To make maters worse, when Corel released version 1 of their Lightroom equivalent in a Mac version, they still kept Paintshop Pro as PC only.