For me the Sheraton wins on all fronts because of various criteria:

-Sheraton lounge is open every day and serves warm evening food every day. (Renaissance serves no warm evening food on sundays)
-I found BOTH food quality and the selection better in the lounge better at the Sheraton (Renaissance had a smaller selection and quality was just ok)
-Sheraton lounge is on top floor with nice views, while Renaissance lounge is on ground floor
-Sheraton lounge is larger

-Sheraton main entrance is closer to the tram stop
-You can open the windows for fresh air at the Sheraton (Renaissance windows cant be opened)
-The rooms are bigger at the Sheraton
-The bathrooms are much larger at the Sheraton
-Sheraton has walk-in showers in every room (Renaissance still has bathtubs)


The only thing that some people (righlty) complain about is the noise from trains passing by next to Sheraton.
To avoid this, just ask for a room facing away from the trains when you check-in.