Pen & ink with light wash?
Ink wash (above)?
Watercolor (above)?
Gouache (above)?
Acrylics (above)?
Computer (above)?
Myself, I would say the ink wash method supports gags and cartoony drawings the best. If humor was the only factor to consider I'd say the whole industry should switch to ink wash (or a black & white gouache equivalent) tomorrow. It's funnier by a mile.
The problem is that audiences like color and so do I. I can't help it, I like beautiful cartoons. In my opinion the color mediums that best support the comedy/beauty combination are watercolor and gouache. Some of the best and most indisputably funny Ren & Stimpy episodes used acrylics but the acrylics were done in a style that often looked like gouache so they're difficult to classify.
Certainly the background medium that supports comedy least is the computer. Can any background be funny if it's colored in a computer? I've laughed at gags in shows that had minimal computer backgrounds but in those cases the job of the background was simply to not get in the way. It wasn't a positive comedic asset, except as a design element. There are probably exceptions to this but I'm too sleepy to think of them.
