Okami I wouldn't really compare to Zelda. If you haven't played 3D Dot Game Heroes, and enjoy the classic Zelda style, I highly suggest you pick that game up. It's Zelda, a bit of a Lego feel, and a bunch of gaming references.
Darksiders- fun. kinda interesting story. Starts off more god of war like than Zelda, but gets there after the first dungeon. Still more like GoW.
Okami-this game in my opinion is a work of art. Graphics/art style looks great. The controls are tight and work very well. The story was fantastic. (This was based off the original ps2 version. I don't have the ps3 one yet.)
I'm actually playing through darksiders now, thanks to ps+ but I like it enough to buy a disc copy. But my vote goes to okami. Especially since you have darksiders on pc no sence in having 2 copies of a game you don't know if you will care for it.