If you trade for the GM, you will most likely be in the "Jungle" GM buildings. Therefore, if it were me, I would choose the GB over the GM. They are built alongside one another and are a rather long walk to the pools/beach along their elevated winding wooden walkways. There is transportation, but that means waiting for carts.
Like Phyllis wrote, 2 small fridges instead of one. The GB units are very nicely done. On the other hand, if you can get GM 1-7 with their location closer to the pools and beach, go for that instead.