Do you use any of the popular cloud solutions, if so, why?

AWS/Azure especially, but even the smaller fry like digital ocean.

Why? What's your use case and why is this the right choice for your project?

 

I used AWS exclusively. The community documentation is the best. Many of their features, like Dynamo, people actually use.

Azure was alright.

I would pass on things like Heztner, unless your players are located in Finland or Germany, where their servers are located.

The biggest problem is poor network speeds on cheap instances in all cloud providers. More expensive instances are not at all economical compared to colocating servers yourself, especially if you have a popular free game with long session times.

 

I've experimented with AWS and SmartFoxServer and was very happy with both. The reason is that AWS cheap servers (t2/3 nano/micro) are more than enough to run a couple 1000s users with SmartFox. Plus AWS is very flexible in terms of configuring your own system. You can setup your own VPC as you like, add elastic IPs where needed, lots of choices for databases etc. Also tried Rackspace (which seems pretty good) but it's much less flexible (fixed server configs) and overall more expensive.