Well as others have pointed out there are a number of things to consider:
1. Budget
2. Purpose
3. Artistic skill
1. The all important $$. Personal opinion aside, if 'free' is your only option, GIMP or KRITA are probably going to be your choices. I tried running the latest version of GIMP on a brand new Mac with OS Catalina and the performance was woeful, it drove me insane. On my work PC I was able to figure out how to recreate (more or less) my Photoshop workflow for Dungeon and Hex maps (for using on my home Mac which no longer runs Adobe CS4). KRITA works much better on my Mac and what I'll be using when needed. CC3+ is reasonably priced and you can get some good deals. I just bought the Humble Bundle for $51AUD which came with 3 core programs; CC3+, City & Dungeon Designer and a host of other stuff. As others have mentioned, you are limited by the art packs you have unless you have the skill to create your own. Then we have Adobe, I prefer this over the free programs as its more what I'm used to but I refuse to pay a subscription for essentially an update to a program I already own. Unless you can generate a reasonable income from it or use it for business purposes (to receive tax benefits - depending on how that works in your locale) I would suggest the other options.
2. If you want to create truly unique, artisitic maps, that are 100% your own, an image editing program is what you need. If, on the other hand, you want to produce quality maps quickly, in a wide range of styles for gaming purposes, whether for VTTs or print media, then I think CC3+ is a good choice and why I decided to go that route. Using Crossover (a paid WINE utility) I am able to run CC3+ on my Mac natively without having to install Windows #.
3. If you've no artistic skill, like me, then CC3+ is definitely a must have. If the reverse is true one of the image editing software programs will probably be more to your taste.
Either way, all packages have a learning curve. I tried the demo version of CC2 I think it was, back in the early 2000's and I couldn't get my head around it (not much internet support, tutorials etc around back then) so I bought Dundjinni and only used when necessary so I never got proficient with it. Now I find myself looking forward to getting down with CC3+.