Each of us has a reason why one hotel is the absolute best and why you should stay at our preferred hotel. The bottom line is while you see many posts explaining why this or that hotel is the best, you rarely see any posts about any of the Paris hotels being bad. No matter which hotel you choose, you are going to have an awesome trip. You will think the hotel is perfect and you won't be able to imagine any other hotel being better. Make a choice, stick with it, and stop over analyzing the choice or you can drive yourself batty.
BTW. a couple years ago I did a trip with family. We stayed at the CE FS. Yes, many on here don't like the property but we had a great trip. At the same time, neighbors were staying at the St Denis CY. They had nothing but awesome things to say about their great trip and hotel. When in comes to Marriott properties in Paris, what makes the choice hard is the all options are excellent.