Mongo DB in Azure ( IaaS) v/s Cosmos DB API for Mongo DB ( PaaS )

Hi All,

Could you please share your thoughts which is the best option for Mongo DB
1) Mongo DB in Azure ( IaaS )
2) Cosmos DB API for Mongo DB ( PaaS )

I know it depends on the required application functionality, In case if we have to evaluate w.r.to cost and generic DB functionality related evaluation which one is recommended.

Many thanks in advance.

Regards
Chandana D M