Without knowing where you travel, what you value in a hotel and a loyalty program, and what your complaints about Starwood are, it's likely difficult to recommend another chain.

What each program will do based on your SPG Platinum status is summarized in the first post in this thread. Hyatt will give you their top tier. Marriott and Hilton may offer you a fast track to status. Priority Club will offer their relatively meaningless top tier (Platinum, as distinguished from the Intercontinental Ambassador/Royal Ambassador levels)...