I would avoid that Anantara Riverside, to be perfectly honest - location is not great, and I find that the property outdoors has an inherently unpleasant smell from the canal that runs through it.

I am a Hilton guy myself too, and Waldorf is brilliant for sure - I can highly recommend it. Conrad used to be my "home" in BKK before I moved here, and it has never disappointed either. If pool area is important, I would choose Conrad over most properties in the city based on this aspect alone. In my view, Conrad is great, although WA obviously is a step up. Location wise, Conrad is a mere 5 minutes walk from Ploenchit BTS, so not sure where the "long walk" stated by someone upthread comes from.