There have always been big differences within the chains, of course, and RC, for example, no longer has a very good overall reputation with me. I still appreciate FS very much, I actually always have good stays there.
Otherwise, I have to agree that a lot depends on the property and the management.
Now you can have different opinions about Aman, everything there is not gold what glitters, but without question it is a very good chain and my last stay was far too long ago.