AWS currently and for the last ~4 years. We have also placed more than a dozen clients into AWS. We have used SoftLayer, Peak10, Google and Azure at different

AWS currently and for the last ~4 years. We have also placed more than a dozen clients into AWS. We have used SoftLayer, Peak10, Google and Azure at different times while testing things out. SoftLayer we actually ran some processes in for about a year. I recently had posted on HN about services like DigitalOcean because there are ways for us to save money using those types of services, or even Heroku. In the end the ecosystem, ease of use, reliability (when architected right) and flexibility of AWS is still just too powerful for us. The costs are not the cheapest way we could do something, but when you factor in the minimal amount of man hours we spend on infrastructure compared to what we could be, I think it is a good deal. We try not to get too ingrained to AWS only features, and where we do we will hide their implementation so we can switch them out if ever needed. I also classify them differently too, for example, DynamoDB or MySQL (via RDS) wouldn't be something I'd try to wrap, it is your database and could be used from anywhere so you aren't really locked into AWS as much as your database there. But something like SQS, we used but wrapped, and eventually moved to RabbitMQ with very little extra effort. I have had to use AWS support a few times, and they have been AMAZINGLY helpful. And for non-critical things they usually answer forum posts pretty quick too. AWS isn't a panacea with no issues, but for my money its the best thing going right now. And they are constantly releasing new things and tweaking things, not everything is for the better, but for the most part it is.