These are NOT reviews, simply my listing what was tried and what was eventually chosen to best suit MY personal needs. I pretty much liked most of these!
Here's what I did use in the past: QuarkXpress, Microsoft Publisher, Macromedia suite (before bought out by Adobe), later, Adobe Photoshop and a little Illustrator.
The official link to FireAlpaca
The official link to GIMP
The official link to Inkscape
The official link to Krita
The official link to MediBang
The official link to JUMP Paint, made by the creators of MediBang software and app and based on Shonen Jump Magazine license
The official link to Paint.NET
Gravit Designer is associates with Google but since I couldn't get a proper link (forums, chat rooms, and mirror sites) from an official site, I'm just going to leave this here.
As I said earlier in my post, this wasn't a review post, just what I experimented with and I only picked what was 'easier and more intuitive FOR ME' to use. All these interfaces and user experiences were fun and enlightening to use, so feel free to try them out on your own!
