Hands down - Westin. I stayed at the Westin a couple weeks back and the place was clean and comfortable. I stayed at the Sheraton Towers yesterday and I am considering cancelling my award reservation over the holidays. I used to like this hotel but this last visit really showed how worn down this hotel has gotton.
First the hallway carpet (on the 34 flr) was dark and looked dirty. The room was kinda dark. The light switch in the Bathroom was dirty - all it take is someone wiping it with a wet cloth. The straw that broke my back was a classic NYC roach crawling across the wall. It did not live long but I did not feel comfortable after that. It was only a one nighter so I did not bother to change rooms.
I think is time for another million $ renovation for the Towers.