I think you need to decide what is most important to you: Location to MK or immersive theming.
The CR is my least favorite resort. It has a fabulous staff, it is wonderfully located, and it has beautiful rooms with an unbeatable view if you stay facing the MK. But I don't feel relaxed there. I'm worried about my kids leaning too far over a railing either on the outside or the inside of the building, the first four floors are bustling and filled with tons of people, you have to take central elevators down to the main floor and walk through the busy lobby to get to the pool, etc. I feel like I'm staying in a high-rise office building and not a resort. The pool is nice, but it has no "wow" factor. And my kids think the slide is the most boring one on property.
We LOVE the GF, and love our new "home" in the GFVs. We love that it's close to the Poly, too, so it's easy to visit. The grounds are gorgeous and the resort is just the right size, IMO, with nothing being too far away or a hassle to get to. If you are looking for an immersive theme that transports you to another place in the world, however, you're not going to get it at the Grand. However, you'll still have wonderful views of the castle and fireworks, the convenience of the monorail, and the luxury of visiting the Poly easily without needing to stay in the midst of the construction. I don't think that the GF is sterile at all, and we have always encountered some of the very best and friendliest CMs at the Grand.
Beach Club, to me, is a more relaxed and slightly different experience than the Grand. I am very fond of the Epcot resorts as we love spending our time in the back of World Showcase and the ease of accessing that and the restaurants and entertainment on the Boardwalk. While we also love the uniqueness of the pool, as a mom of differently-abled swimmers, I don't find that I can quite relax there as I'm trying to keep track of all three of my kids, all of whom enjoy different areas of the pool.
Other ideas for you would be Wilderness Lodge and Animal Kingdom, both of which I haven't stayed at (yet), but both seem to be the only other two deluxe resorts on property that have fairly immersive themes. I also think that the color schemes and aesthetics of the grounds and resorts would be similar to what you're used to with the Poly.
If you're open to a split stay, that's an option too. We are huge fans of doing split stays when trying new hotels as it allows us the option to try something new without committing the entire vacation to the new resort in case we don't love it as much as somewhere else on property. Personally, we find hotel hopping to be easy and pain free at Disney if you pack with the move in mind and don't mind being possibly "homeless" for a few hours of your moving day.