I spent a bit of time at the beginning of the project evaluating the two and ended up choosing chef because it was going to be easier to use this way (aka build something on top of).

I will say that it was easier and far less confusing to get puppet up and running initially. There's definitely a bit that needs to be worked out in the chef documentation. The "Ruby"-ness of chef wasn't really a deciding factor as I can work with just about anything as long as it's reasonable.