I am booked in a Standard View YC CL room for the end of May but could move to Sugarloaf at the GF for about $150 more total for the length of the stay. Are the offerings in the lounges much different between YC and Sugarloaf?
In fairness, it has been a few years since I have stayed at either, but we felt the food at GF was a little bit better then the rest. Someone else can give you better food updates, but I think GF still offers the unique afternoon tea time. (not a huge deal, but still unique)
I'd say the bigger difference though is the things that don't change, like location and square footage.
GF is on the monorail loop, which means you can dine any place on the monorail loop quite easily. It is also close to MK, which used to be open late most days. In 2019, not so much.
YC is walking distance to both Epcot and HS, which will become a bigger plus come August 29, when the new SW starts to open. You get easy access to all BC/YC/BWK/Swan/Dolphin and WS eateries (with park admission), but none of the pathways are covered. In heavy afternoon rain storms those paths can be rather wet. In nice weather, uncovered paths are super. You can also get around via shuttle boats, but they aren't super fast.
They both have very nice pools, I suggest looking at images of each if the pool is important to you. Much of the YC main pool has a rather unique sand bottom, including a kid sand play area. The GF pools are also very nice.
Rooms at both are quite spacious, but GF is bigger.
GF/CR standard rooms are 440sq ft (though I think the GF room layout/allocation of that 440sq ft is much better),
YC/BC=381.
To compare other WDW hotels you may have tried: WL/AKL=344, Poly is 415, Bwk=371, mods=314, values=260. This is a big part of why you will most often see AKL and WL for lower rates, while GF is often the highest.
The downside of standard Sugarloaf, within GF, the rooms and lounge do no offer views of MK. It is not located in the main building, so you can't hear the live music (only the more $$ CL at GF), and if you want to eat anywhere other than the lounge, you have to walk outdoors. This matters when you want to dine at V&A or Citricos during a downpour.
Overall though Sugarloaf is a great building location. It is right next to the GF quick serve place.
Sugarloaf is also relatively close tot he GF convention building. If you are at GF for business, Sugarloaf is a plus.
There's also the new gondola, but I'm sure about construction or the opening.