That's tough... we love them both!
Cape May... works out great on an Epcot, even DHS day. We love the food there - such a nice variety (and we don't even like seafood and find tons we love on the nonseafood side!) Definitely a great meal!
Whispering Canyon - fun! We enjoy the food there a lot. Lots of stuff there has a smoked flavor to it, which some may not care for. I actually prefer the ribs at Cape May wayyyyy over WCC's ribs to be honest. But oh, yes, food is good, but is a more fun experience than Cape May.
Both have good food - but I think Cape May's is better and more variety - though WCC is lots of fun. Nice little boat ride over from MK on a MK park day.
any way you could do BOTH?
Oh, and my kids would probably say WCC. They have lots of fun there and like the hobby horse rides through the restaurant and the whole ketchup bit. For kids... I'd say they'd enjoy WCC a lot more and is more memorable than WCC for them!