My DD is pretty sensitive to smells, but she has never reacted to it at any of the WDW restaurants. Of course, her sensitivity to sound is much worse than smell. We bring noise reducing headphones, but lately she prefers to use her ipod and headphones. She can't stand earbuds so she uses the old style headphones that go over the ear.
As for favorite restaurants, she has several. Crystal Palace is a must do for us. She liked Be Our Guest, which surprised me because I thought it was loud in there, but I think the idea of eating in Beast's castle out did the discomfort from noise. Liberty Tree Tavern is a favorite for lunch, but not dinner. We prefer the lunch menu. At Epcot, the only table service she really liked was LeCellier. We usually do counter service places in World Showcase. She likes the Liberty Inn, but she is a picky eater. Her favorite in Hollywood Studios is 50s Prime Time Cafe. We don't really have anything in AK that we love.
At the resorts, Beaches and Cream and Whispering Canyon are favorites for her.