Like a lot of the others have said, my favorite is the Storybook Cartridge. I also like the A Child's Year cartridge too for the neat silohettes and font. Since purchasing SCAL in Sept. I haven't used my cartridges all that much lately. I am having a lot of fun downloading pictures, tracing and cutting them out. I just finished making 180 lollipop Ruby Slipper favors and 33 Munchkin tags for a benefit auction using the SCAL program. Here are some photos on how they turned out.
Munchkin tags on bags
Ruby Slipper Lollipop party favors