*throws his two cents into this battle...errr....discussion*
I use Paintshop Pro X2. I've used it since the early days in Windows 3.1. It serves my purposes fine. I've also used the GIMP and have even bought books for it. The GIMP would work fine too if I spent more time using it.
If you're looking for a GIMP alternative that looks sorta kinda like Photoshop have you thought about GIMPShop? It's the GIMP but with modifications to make it look/feel a little like Photoshop. It was started by the person that owns the plastic bugs blog. Here's a link to the GIMPShop page where you can download it and find some tutorials.
http://www.gimpshop.com/index.shtml
In my personal opinion it comes down to the eye that captures the picture and the eye that modifies it. Use what you're comfortable with. *shrug*
Good luck with the GIMP.
