I prefer the Westin, I can't stand the heating/AC units in the Sheraton. The ones that have a 'hot/cold' dial, and a fan that must be 'ON or OFF'. I can't sleep well with that racket. The rooms were comparable, the location comparable. The 'River Front' is nothing fancy IMO.
I did the Westin one week and tried the Sheraton out for a night before I switched back to the Westin during my 2nd week there.