We've eaten at both on different occasions. Have had a great meal at both. However, I agree with the "stuffy" atmosphere of Shula's. I liked the atmosphere at YS. Shula's is dark, no windows, at least where we sat. YS is a little more open, I like that better. I also like to wear my shorts and sandals during the length of my vacation, that didn't feel appropriate at Shula's. Nothing wrong with that, just not what I want.
You won't go wrong with either. I have not tried, but have heard excellent reviews about LeCellier in Epcot, Canada. That may also be another option for you too.