Actually, I would say the best cloud support comes from Rackspace. You actually get a phone call welcoming you and walking through the product, they have Cloud Advisors who will talk you through optimizing performance and if you pay 100$/month extra, someone who will configure and maintain nginx/mysql/haproxy/rails/django/etc.
As long as we're on the subject: anyone here use their managed tier of hosting (VPS or dedicated)? I'm on their standard Cloud Servers (VPS) after having been force-migrated when they bought Slicehost. My experience with their support at that level has been... uneven. If managed means I get their best guys touching my nginx config files, I'd buy that today. If it gets me someone drawn from the pool at random, I'd run screaming.
That's my experience with Rackspace. They're fairly inflexible in what they offer, and it's a bit of a pain to go outside of their standard offerings, but if you can work within their limits then they offer truly unparalleled service even for tiny 'insignificant' customers.
I tried Rackspace but there's no equivalent of AWS's elastic IP, so if you stop the instance you lose the IP address. It's ok if you go through load balancers, but no good for a single site with a single IP.
