I've always been fond of the Scribblenauts and Drawn to Life series, as well as Black and White (one and two)! I also enjoyed Spectrobes for a while, haha. If I had to pick a top favorite, though, I'd have to say Drawn to Life: The Next Chapter. It was colorful, fun, and addictive, with a flawlessly executed storyline complete with the most heart-ripping downer ending of all time.