While I don't know much about Houston, I have stayed at both the JW and the FS in the Galleria area recently and can offer this perspective. The JW is a very, very nice hotel. The FS is a very, very nice, but not as nice, hotel. Both are on my stay-again list.
Price being my factor, the FS is actually often a bargain, so it wins. The rooms were non-descript up-to-date FS. The employees were above-and-beyond helpful at every turn. (And, in the case of the evening CL Attendant, almost oo much so.) If your plan is to do little more than sleep in the room and use the CL, this is a good choice.
If you do stay at the FS... someone at the front desk recommended the Greek restaurant around the corner from the hotel. It was awesome.