We deliver video content. We have a CDN that properly encodes and serves our content. All I need is to handle the HTTP requests for the "directory" of videos. A shared environment would probably be fine. All the 4GB servers seem to have most of their RAM dedicated to caching when I check what free -m gives me. Our physical disk space requirements are low. As I shift more of our content to the CDN, our bandwidth needs are decreasing as well (from 12TB/mo to 7TB/mo since I started optimizing).
I inherited this setup, so to me it looks like the servers are overpowered. Also, the customer service is terrible, which is the primary reason for wanting to leave them. I want a service where I can easily requisition and kit out new servers quickly in an "a la carte" fashion.
I have 3 servers running on EC2 already using micro instances. They're mostly to handle minor services (email list subscription/requeuing for all the web properties, payment processing postback handling, etc.) They've been up for nearly a year without any problem.
I've been leaning toward EC2, but I wanted to hear what else is out there.