Gentleperson,
my five cents: I think the best photo is the one you like or the one which induces joy in the ones you present it too. This has, as for example
@Deepdiver above put it, some artistic aspects.
Basically there are at least 2 steps after you have taking a picture:
* first you “develop” your picture - exposure, details, color saturation, tonal contrast, etc.. Photos in RAW format offer the maximum possible at this step to optimise these parameters of a good picture to make it into a better one. There programs or apps for this step e.g. Lightroom, Capture One, Affinity Photo, Apple Photo, Google Snapseed, Pixelmator Photo & Pixelmator Pro, and more. (Many of the parameters you can adjust in a RAW file you can technically adjust in a JPEG, to get a better understanding on digital (pro)RAW I recommend
this blog entry from the creators of the Hallide camera app for iOS/iPadOS.
* and then there are programs or apps which offer additional filtering, sophisticated machine learning tools, compositing, etc. While some of the “developer”programs and apps mentioned before integrate and offer this - it is the domain of Photoshop, Affinity Photo, Gimp, Nik Collection/DxO, Pixelmator & Co.
Additionally you might need some form of photo management software/app: Apple Photos, Adobe Bridge&Lightroom, Darktable, Pixelmator Photo, etc. provide this functionality.
What is best, you ask? In my opinion there is there is no definitive answer to that. Personal preferences, requirements or restrictions, knowledge, field of work, access to people who use particular programs or apps, laziness, support etc. will make people choose something to create some kind of workflow to end up with photographs they like a lot.