Having used Linode, SliceHost, and AWS I would say they are all about the same.
I had a severe crash at Linode years ago causing a complete loss of data. They did work with me for days trying to recover the filesystem and I found their support staff knowledgeable and helpful.
I never had problems with SliceHost so I don't know much about their support.
I'm using AWS because a reserved micro instance is super cheap at just under $10 and because I manage a much larger AWS infrastructure at work so it's nice to work with the same APIs for my own stuff and work. I also think the skillset is more transferable if you're learning.