Should I use ImageMagick, or GD2, with ImageAPI in Drupal? What are the pros and cons?
ImageMagick
On the downside, it is not available everywhere and as @Nicholas Goy says, a heavy dependency. But when I have the choice, I use ImageMagick.
If you can avoid ImageMagick, then avoid it.
ImageMagick is a heavy dependency that might not be present everywhere, while GD is more often available.
As for the drupal specific question, I don't know how it integrates with either, so just take my advice as a deployment consideration.