I didn't even know paint shop pro even exsists anymore?
I haven't used paint shop pro in like 20 years lol!
When I studied graphic design in school, I started on paint shop pro, but we quickly transitioned over to photoshop as the superior graphic design program. I haven't used it in 20 years so I can't really speak for it now days, but on first glance, it's a one time payment of $64, meanwhile photoshop is like, $50 a month, so that right there makes paint shop pro far cheaper (though supposedly you should be able to do everything in GIMP which is free)
I see in a comparison page on their site, that they say Photoshop isn't dual monitor compatible. You only need your tools and menus on one window, but you can work on multiple documents on multiple windows, so they're wrong about that.
You can try BOTH of them for free as a trial, so you might as well give both of them a try for yourself to see which one fits better with your style. I've been using Photoshop for maybe 15-20 years now (god I feel old now) and I absolutely love it. I learned to use Paint Shop Pro in high school, and then when I got into design class, the teachers taught me "how to use a PROPER graphic design program" which was photoshop.
Though Paint Shop Pro is $72 for life (maybe cheaper with vegas pro, and if vegas pro is one price for life with no subscription price, you may as well go with that) really though, just download the trials and give them both a go for yourself. They're fairly similar.