I use GIMP too but I plan to switch to Photoshop because GIMP is a bit annoying and a bit limited. After many years, I've had enough.
I use Inkscape for really simple things such as saving the file in a different format, as working with vector graphics is among the few things in life I can not do. So I usually just hire someone to do it.
Just use GIMP. It's powerful enough, it's free, and could last you a long time without a need to switch to something else.
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