It's easy to get started with D.O. but Linode's interface is much easier if you need to upgrade. Last I checked, D.O. doesn't even have an option to add more disk space. With Linode it's just a few clicks to resize.

With D.O. there's an ambiguous list of things you need to do to upgrade to a new plan. For example, after shutting down to upgrade, I heard you need to backup your disk image to multiple datacenters because sometimes an image can get deleted by accident. One night I spent several hours trying to (safely) upgrade and support was slow to respond, eventually I gave up. With Linode it's just a few clicks and you can see the progress of the migration in the dashboard, it's very easy.

I use both Linode and D.O. but for personal projects, Linode is my choice because their tech support team is very responsive 24/7. I am not a heavy user of tech support but when I do need help I need it fast!