What an odd question, interesting, but odd.
Anyway, I use WindowMaker, so its dock apps for me. Though I used Gkrellm in Fluxbox.
I use dockapps for a few things:
I easily found dock apps for these, because theres THOUSANDS of them (theres a + for dockapps).
I also like them, because they work well w/ the dock (duh).
Dock apps seem to be more versitle to me.