Besides the UTTERLY obvious answer here, I'd say that after Excel, my favorite characters are...... Hmmm.....
Well, in terms of how funny I think they are and how much I enjoy seeing their antics, my choices would go as Il Palazzo, Iwata, and Shiouji. The thing is that I don't really like many of the other characters by themselves. I like watching the interaction between the Daitenzin guys as a group, but by themselves they'd be pretty boring and uninteresting. I mean, even Iwata. Thick as a brick he may be, but apart from the others he's actually pretty normal. ...... Y'know, 'cept for the cyborg bit.
I think Kabapu's funny, but I don't like him. I ALMOST feel bad for him (lol vol. 16), but I think it's really just divine retribution. He earned it.
So yeah, I stick by my choices.
1. Excel
2. Il Palazzo
3. Iwata/Daitenzin dudes
4. Shiouji