Both places are very good, different menus and different atmosphere. You may have to wait at Beaches and Cream. You probably won't have to wait at the Yacht Club Galley. Honestly, you can't go wrong with either choice.
You can make a reservation at Yacht Club Galley (probably even the day before) and it is much quieter than Beaches and Cream. We had a great dinner at the Galley but had a ery disappointing meal at Beaches and Cream and that would make the difference personally for us. My husband loves burgers and did think Beaches and Cream had good ones. But the service, or lack thereof, was so bad (we are patient people normally) that saying we're going to Beaches and Cream is a joke between the two of us. That's just our personal experience but the lack of being able to get a reservation at Beach and Cream is the downfall for us. That led to why we had the very disappointing meal there. We both wish they had the burgers on their To Go menu.
I'd try YCG. DS and DDIL just came back from WDW. They ate lunch at YCG one day and DS raved about how great it was. He called it "the hidden gem" of the World. Among what he raved about was the cheesecake he had for dessert. He called it the best ever!
It depends on what you're looking for. If you want a nice relaxing lunch with room to move, YCG would be my choice. They have excellent burgers there (which is the main thing people go to B&C for). The only reason to go to B&C over YCG in my opinion is if you are interested in the ice cream. You won't find the ooey gooey sundaes at YCG. Of course, you could get lunch at YCG and stop at the B&C take out window for ice cream later.
Think I'll make an ADR for YCG...then when we get there will decide then...since you cannot make an ADR for Beaches and Cream, guess we better be safe than sorry, right?
That's a good backup plan. You can always cancel YCG. But then again, you likely won't even need an ADR... it really is a hidden gem. My vote would also go to YCG, incidentally, because B&C has a crazy wait usually, and feels too rushed.