There are different kinds of applications used in an Enterprise. Is it a good option to move the entire set to cloud or do we need to move only certain applications? which is beneficial?
Usually a migration to AWS starts with a small and non-mission-critical application. Afterwards all other applications are moved to AWS step by step.
It is possible to use AWS as a hybrid-cloud connected to your on-premise infrastructure in the beginning.
If it is worth to migrate an application to AWS depends very heavily on the specific use case. But as it is valuable to transfer the most applications to AWS it might also be useful to migrate the few remaining applications as well to be able to get rid of the current datacenter.