I've used and had good experience with both platforms. The only performance issues I've ever had were with SimpleDB when it was in beta. For support the nod w

I've used and had good experience with both platforms. The only performance issues I've ever had were with SimpleDB when it was in beta. For support the nod would have to go to Rackspace, in my opinion. The two times I've needed help I was talking to a real person in San Antonio within twenty seconds or so, which beats a post in the AWS forums that might eventually get answered from an employee if your lucky.