I use FireAlpaca for drawing and colouring my comic pages and I do like it. It reminds me of Open Canvas, which I used a lot when I was younger. For a free program I think it's great and works well if you don't need any fancy tools. For anything fancier I do suggest trying Photoshop.
Honestly, I think any program can be used to create good art and it all comes down to personal preference. I like the simplicity of FireAlpaca but for some it might feel restricting. It's worth trying out, though.