Only way you can properly figure this out is by monitoring. You are at luck we have a plugin:
For a low-mid traffic site digital ocean is probably going to be just fine, but you should use a CDN. If you want less server time opt for high CPU droplets.
Amazon offer an army of servers to pick from, depending on what you pick it may be slower or faster.
Also nothing stopping you from using CloudFront and S3 on Digital Ocean.