I use GIMP.
Contrarily to what is usually said, GIMP is easy to use for pixel art:
- use the pencil tool
- with a 1 pixel brush. Done.
Plus you have all of GIMP’s powerful features ready, would you need them.
Tried few others software specialized in pixel art, never liked them that much.
For me the decisive feature of GIMP is complete freedom with keyboard shortcuts.
They can be customized, so I can really enter into “the flow” because they totally suit me.
In the end, the tool doesn’t matter much, it’s how comfortable and productive you are with it.
I tend to use as few tools as possible, so I become really productive with them.