I don't know the W or the Pickwick, so I'll just offer my personal opinion on the other three. The Marriott is a large convention hotel. Nothing wrong with it, but I find it a bit sterile. The Argent is the former ANA. Again, a good basic hotel, little to complain about but nothing special. So that leaves the Sheraton, which would definitely be my choice among those three. The Sheraton has a distinctive and unique ambience that sets it apart from most other downtown hotels and has a real feeling of class. You feel as if you are somewhere special when you are at the Sheraton.