I have been at both.. They are both really good hotels, but the Hilton Prague beats out the Prague Old town. Even if you take in to account the location. Sure the old town is better, but the Hilton Prague is a quick walk or cab ride away. As a Diamond the Hilton Prague treated me much better. Last time I checked the Prague Hilton is also running point saver stays almost everyday of the year. I'm going back in Dec and already have my room booked at the Hilton Prague, they also offer a nice car service from the Airport. No matter what one you pick you will be happy, but I like the Big Hilton Prague. (PM me and I can give you an email for a contact I have at the Hilton Prague)