Paint Shop Pro, GIMP, Paint.NET and Photoshop
At home, I use GIMP and occasionally Paint.NET on my windows machine. I did have PSP v8 but lost the disc - used that for every photo edit.
At work though, I use Adobe Fireworks and Photoshop (on an old CS3 installation) - does the job perfectly and has a definite speed increase as opposed to the products mentioned above. can find that there is a function or utility that does what I need to do and layer work is so simple in Adobe.
The other products (and I do like GIMP) still have a fair bit of catching up.
I just wish it wasn't so stupidly expensive. I think work paid a few thousand for our CS3 licences (but it was the full CS3 Web Premium suite). I also wish they hadn't gone all cloud based.