Between the Westin and the Sheraton, I would always choose the Westin. I think the rooms are better and larger, and it doesn't feel as depressing or old as the Sheraton. But I would avoid all those hotels (including the Hilton Tucherpark and the Marriott) as the location is pretty poor. The Meridien is in a better location than the others, but this area, around the Hauptbahnhof, with its 'issues' (drunks, red light district, punch ups between groups of often refugees) also reflect on the better Sofitel and Königshof hotels. It's not nice to come home to. In my view, the best location is still around the Maxilimiliansstrasse, but you get what you pay for!