I don't think there is a proper answer to that question because I think those two programs are too different to say which one is "better". Open Canvas (as far as I know) is a program especially created for digital art which provides lots of different brush tools an artist needs to create wonderful digital artwork. Ah, yes, and you can rotate the canvas like you would do with a sheet of paper, very useful for inking. Although you can also create great artwork in Paint Shop Pro (and lots of people actually do), it's not an art program. Creating digital art is only one thing you can do with Paint Shop Pro, you can also use it for photomanipulation and for creating avatars, wallpapers, layouts for your website or stuff like that. I would recommend you to download a trial version of both and then buy the one you like better and while testing: what about trying GIMP? In some points its as "powerful" as Photoshop and it's freeware.