You could compare Digital Ocean to Amazon Lightsail. or to Heroku. But Lighstail is only one of the many services provided by AWS.
If you only see some easy to use servers, then you could compare and decide. If you need these servers to be part of a larger solution, with complete control of your network topology between your instances, with massive scale databases, fine-grained permission policies, dedicated link with your on-prem infrastructure (hybrid cloud), audit logs for compliance reports, 'infinite' object based storage with crazy data durability (the famous S3 eleven 9s), and some CDN solution, plus some serveless features, plus this, plus that (I won't list them all, there are hundreds of services and features)
In short, AWS could be compared to Google Cloud Platform or Microsoft Azure.
For any other solution, you're only going to compare it with a small subset of one of these big IaaP/PaaP providers has to offer. And if you only need this, it might be a perfect fit for your current needs. (These smaller providers try hard to have a valid business model by providing some ease of use or optimized-for-something solution, because for the general use-case, they just can't compete any longer with the 3 big players.