AWS has entered the cloud field well before Azure and is one of the most fav. Though Azure has entered the cloud war later than AWS, it has made a significant mark in the cloud domain. Now going to the comparison, 
AWS has the following pros over Azure:
- Data is easily available 
 
- High Transfer Stability
 
Azure has the following cons:
- Low Quality Support
 
- Restrictive Platform
 
So according to me, AWS as a career will be more promising than Azure