Eh. My version of Corel is from the mid-eighties, I believe (doesn't run on anything fancier than Windows 3.1, last I checked), and I've never really used PSP much, so I might be biased as to what I KNOW I can do, but it seems to me that Photoshop is... well, it's the standard for 2D, and it's that for a reason. It's possibly the most comprehensive tool I've ever seen for what it does, and it's getting more so all the time. There's next to nothing you can't do in Photoshop if you know how to go about it, and the endless third-party plugins make up for the rest.
'Course, I use it a lot of the time for a lot more... advanced applications than texturing and Glitterato. Since I'm a photographer, I probably get exposed more to the field Photoshop was really made for- However much it is becoming a paint app in its own now, it's really supposed to be an image editing tool, not an image creating one like PSP and (last I checked, which might be fifteen years ago) Corel.