get photoshop elements if your concerned about price.
if your concern is the learning curve, all are quite easy to learn, harder to master, paint shop being the least hard to master becuase it lacks more advanced features.
if you just want the best one, photoshop CS2 is what you want, If you get the CS2 creative suite, you also get a bunch of other great programs to go along with it including GoLiveCS2 which is a great web development software, often over looked by dreamweaver fans, which is now also owned by adobe