Whilst I haven't stayed in all of those hotels, my answer to these is always Tower Bridge. Rooms nice. Bankside newer but rooms seem darker to me. Right across from London Bridge Station/tube. Better range of food options nearby than Bankside or Conrad. You have Borough Market, vinegar yard (small outdoor stalls/street food), lots of places between the hotel and Tower Bridge. Not yoo much further to Bermondsey for the craft beer mile and Malty St Market. Depending on when you go the lounge has a nice terrace too and I would rate food over Bankside.