I've worked with linode, do, and aws over the years. I'll skip do as they're fairly similar to linode but I haven't used them enough to have explicit examples, and will therefore compare linode and aws.
Off the bat, you get a lot more bang for your buck at linode, in terms of compute and storage. If you're running a single server, don't care too much about what's on it or having many nines of uptime - go for linode. I still use them for hosting a few dinky personal projects.
If you're looking to do more though, say something involving hundreds of instances and thousands of interactive requests per second, and every second of downtime means real pain, then raw compute is far from your only consideration.
When we had dire issues with jitter on the xen packet scheduler with linode which was causing memcached requests to get stuck linode support really tried, but drew a blank - we had to tell them the solution and beg them to implement it, which they did - but it took a month, and it cost customer confidence, revenue, my sanity. It's little things like being limited to 50Mb/s node interconnect that make life unnecessarily hard. I absolutely understand why that was the case there, and was very grateful to the folks there tweaking our XPS settings so we wouldn't end up with our packets essentially being quantised, but it was the kind of thing that you really don't want to have to deal with - like moving into a house (admittedly running a heavy industry out of it), and then finding that the windows emit gamma rays on Tuesday when it rains - it took an absurd amount of work to figure out what was going on.
We moved to AWS in the wake of this and other similar issues. Big. Bureaucratic. Expensive. Reliable. Knowledgable. Cheaper than failure.
While since moving to aws we saw occasional and sometimes substantial weirdness within amazon's stack, they would always escalate and resolve major issues very swiftly. The longest we ever waited was a week, on something that required a global change, as we'd discovered a major problem with failure behaviour of one of their beta services. They talked to us every day. The management tools and api are comprehensive, the ecosystem encompasses most services you might want but doesn't get in the way of rolling your own, and they're remarkably flexible in what they'll reconfigure for you if you ask with a good reason. Paying £100k+ a month probably didn't hurt either.
The long and the very short is that you aren't purely paying for hardware when renting compute, you're paying for everything surrounding it. AWS cost more, but for the peace of mind of being able to straddle AZs easily and to know that if something on their end goes bang they'll fix it quick it's worth it.
We managed 97% uptime on linode over two years, five nines on aws.
Oh, and as an aside - when you're selling a SaaS solution, your customers have a lot more confidence when you say the basement iron is Amazon, rather than "sorry, can you repeat that? Lipode? Lytrode?".
I really don't want to bash the linode guys - Chris was really helpful in the early days, and the personal touch was awesome, I saw a lot in their "DNA" that was like ours, and as above, I do still use their service - but AWS is kinda in a league of its own when it comes to provisioned compute services.