Actually, I like ImageMagick (the tool itself) very much, it is very powerful, and with plugins like GhostScript
even more so. I just didn't like the Perl interface. Mind you, it was quite some time ago I tried it last. It might have grown better.
I haven't used GD much, but I've seen what others do with it, and that is likewise a very good package from what I can see. What one uses is probably mostly a matter of what is appropriate for the task at hand and what one likes. Though I *think* that GD is more for creating images, while ImageMagick is more suited to manipulating existing images. That is, if you want to produce charts, graphs or anything like that, GD is probably much better. If you want to create thumbnails for a huge photoalbum, then ImageMagick sure is a great tool (and here I don't know about GD).
You have moved into a dark place.
It is pitch black. You are likely to be eaten by a grue.