Well from a purely CL perspective, in my opinion GDT CL is a ‘better’ CL than YC (and I’m a fan of YC CL). It’s new, amazingly beautiful, a nice large lounge, etc. Pre-COVID, GDT had excellent offerings and a variety of lounge amenities that were frankly probably #1 among the various CLs (my opinion). Assuming they pick up where they left off, it’s a really good CL experience, in my opinion.
But obviously there are big locational differences between YC and GDT. While I don’t mind the bus only access from GDT and I really like its overall central location, for a 6 day trip which I’m assuming will involve at least a couple of trips to Epcot or DHS, it’s really hard to beat the walkable access from YC. It really shifts the planning/approach to a trip when you’re within walking distance to a park(s). The whole Epcot resort area is arguably going to be more “fun” for adults than GDT and more options for dining, if that matters at all for you.
I tend to usually say go with your park plan and pick the location that best suits where you’ll want to spend the most time. Ultimately I would have no qualms about either, and I think GDT CL is typically a great value relatively speaking to other resorts,
Probably not much help since I didn’t really pick a side there.

Hope it helps, good luck with your planning.