Actually Houdini is by far the most powerful tool for motion design in my humble opinion.
Curves, dynamics, volumes, channel operators and particles are just amazing and can be used for graphic purposes even if they seem dedicated to VFX.
The typography tool is a bit clunky but you can deal with it with some little tweaks, same for the awfull deformers that don't even compare with c4d's comfortable ones.
It is not as simple as C4D of course because of the huge possibilities it offers, but in case of complex mograph/expresso set up, the difficulty is quite the same in both app.
The UI is just amazing once you are used to it and once you understand that you can just link anything to anything.
The "bridge" with c4d is indeed a great thing.