The Hyatt hands down. The Hilton is nice but the location is rather characterless and requires a taxi to go anywhere. The Marriott is right on Plaza San Martin at the start of Florida street, it's a nicely restored older building and handy for walking around but I find this area a little hectic. The Hyatt is right smack in Recoleta, a lovely area with allot of trees and parks, great old french style buildings, lots of shops and restaurants, and of course the whole Recoleta Village/Cemetary area is a very short stroll away. It is also a shorter cab ride to the trendy areas of Palermo Soho and Hollywood when you want a change of pace. For the last three Jan/Feb's I have been watching them build this place and when I left this year it was looking pretty good.