To me, the Starwood Card is the best, because on a $ per point basis, hotel awards usually come out ahead. AMEX points convert to Starwood points on a 3:1, whereas with this card you get 1 Starwood point per dollar spent, get a bonus for spending at Starwoods, and get upgraded to Starwood Gold, which has gotten me upgraded 70% of the time, and earns a 50% point bonus. I just stayed 8 free nights at Sheratons in Morocco by using these points!

I, too, recommend the Starwood Amex, but also make sure you get a Visa/Mastercard. Why? Because Amex isn't accepted everywhere and you want to get miles for every dollar charged.

Which Visa to choose? I'd take the affinity card associated with the airline you fly most. Also make sure that airline flies where you want to take your free trip. For example, don't take the US Airways card if you only want to go to Hawaii.