Best Option for REST API Authentication Session Key or OAUth 2.0

Hi Team,

I would like know best Option for REST API Authentication Session Key or OAUth 2.0 

What are Pros-Cons of using Session Key for REST API Authentication  ?

What are Pros-Cons of using OAuth 2.0 for REST API Authentication  ?

 Any suggestion ? 

Thanks 

Sachin Patil