I have stayed in a GV at SSR, AKV Jambo, and BLT.
The Jambo House GV was incredible. The room was absolutely stunning, and the pool table was a nice bonus. Three huge balconies for animal viewing. The only minus here I can think of is getting to the parks is not as convenient as some of the other resorts. Also, it is pretty quiet at night, which would be great for some but a minus for those looking for things to do after dark. I don't know the actual square footage of the three GV's we've stayed in, but this one felt the most spacious. This was, by far, my favorite room I have ever stayed in!
We booked a lake view GV at BLT, and were given one of the rooms that also has a view of the castle. This view was the best view I have had on any WDW trip. Nothing like having your first cup of coffee in the morning, or a glass of wine in the evening, while enjoying the view of the castle from your balcony. We did go to the Top of the World Lounge once, but decided we preferred to sit on our own balcony instead. It was very convenient to get to MK since you could walk.
Our stay in a GV at SSR was fine, it just felt pretty ordinary, like you were visiting someone's house. The balcony was fairly small, and if I remember correctly, there was only one of them. The view from the balcony from was simply looking at rooms across the building. I love my balconies, as you can tell, but had very little interest in the one at SSR. Convenient if you wanted to spend time at Disney Springs, not as convenient getting to the parks.
I hope it works for you!