To the best of my knowledge, the Island Shangri-La has neither a club level nor a club lounge. (The Kowloon Shangri-La has both.) It is certainly true that You'll get upgraded to a suite for free or for US$25/night, depending on Golden Circle level (and availability of course).

And I think we are agreeing, mostly. Both hotels are superb. The Shangri-La certainly has the reputation, but after staying at each, I simply don't see the choice between the two as being at all clear.