My husband and I went to both restaurants, both for the first time last September. We have very different perspectives wen it comes to food, so I'll give you both our opinions, maybe it will help.
Me: I would say Chefs de France. Not because Le Cellier was bad, but because I really enjoyed Chefs de France and our waitress was excellent. She made recommendations, and following them, lead to

. I had the salmon dish, lobster bisque, and creme brulee. My husband had the romaine salad, roasted chicken, and profiteroles. (We were on the dining plan, but it was a Prix Fixe. Both meals were great.
My husband would say Le Cellier. He loves steak, specifically Filet, and while I know Le Cellier may not have the best filet anywhere, it's something we definitely don't go out and have when at home. Our waited, while polite, and expedient, was not as good here. He did not keep up with our drinks, which irks my husband. We both had the filet, and both enjoyed them very much.
As others have said, Le Cellier is more of a steakhouse. It is also a bit dark in there, and cool (which makes sense given the name.) It was also relatively quiet, which was nice for the two of us. Our ADR was at 3:00, I don't know if that made a difference. Chefs de France is the kind of French food I'd like to think my mom would make, if we were French. It is also much brighter, and you can see the people walking by. It was also a bit noisier, but just people talking, no screaming kids or parents. I think to make the choice you'll have to figure out what you want to eat.