Both hotels are terrific. The Hyatt is more austere and modern, however. Even though the FS is a bit corporate, I had a warmer feeling staying there. Service at the FS is outstanding. Though the Hyatt is on a nicer tree lined street, right outside the door of the FS are 2 of the top restaurants in BAires. One important factor may be when you are going: the FS has perhaps the best outdoor pool area in BAires, along with the Faena. Incredibly, the Hyatt doesn't have an outdoor pool. If you are heading in the warmer months that could be a real plus.