Do you mean Sindhorn Kempinski? Also what is the price difference / which categories of rooms are you looking at as it’s difficult to say without this.

I’ve stayed at all three in the last twelve months - PH had the best service, pool and breakfast, Rosewood has the best hard product in the rooms, Sindhorn Kempinski has the most generous room size and best general ambience. There isn’t a clear ‘best’ so it depends on what you value and cost.