Ask HN: Which is better to start with: Xen VPS or Amazon EC2

I'm looking into hosting options right now and I'm starting to get sold on Xen VPS. This raises the question: which is best to start with: Xen VPS or Amazon EC2? For Xen VPS, SliceHost and Linode seem to have the best reputation. I've also heard recommendations for prgmr, vps link, and server axis. At this point, I'm thinking that a Xen VPS solution is best for development and then possibly moving to Amazon EC2 when I'm ready to roll out for real. Any comments or suggestions are greatly appreciated. Thanks.