DynamoDB is key-value based NoSQL and no maintenance is requires except throughput(read and write) provisioning on each table. Data replication is done automatically behind the scene.
I can see very less maintenance in DynamoDB.
Should i use MongoDB for any good reason in cloud?
What are the usecases where MongoDB is better than DynamoDB?
This is a very subjective question – without any context, its impossible for anyone to recommend which to use.
Which database is best for you depends on a wide range of things, including but not limited to
You need to think about your application and understand things like what I’ve listed above and figure out what you need out of a database. Then you need to understand each of your options and which will suffice.