We have done Auberge, CM and Inventions. They all bring different things to the table so to speak.
I think CM has great character interaction but have never rated the food or the service that much. It can be a reasonably cheap character meal though as you can just pick off the menu which can be priced OK. Looking at the ages of your children and the fact you have a girl and boy so need characters for them both, I would probably say CM.
Auberge is more for girls as it's Princess themed.
Cowboy Cookout might be OK too - haven't eaten there. If your DS likes Woody etc it might be a good one.
Recently people haven't liked Inventions so much. I liked it but I do think it depends on the characters you get which can be pot luck and it is expensive (it is also only a Sunday brunch or evening character meal).
When are you going? If the parks are quite quiet you might decide to just try meeting characters in the park and just grab a snack. As you only have one day, you might want to see as much as possible...?