[dhirajbajaj]

It depends what your app stack requirement is.

Google appengine is PAAS based, has competitive features and low priced than AWS EBS comparative. Google compute service is IAAS based and EC2 comparative.

I found, transition from AWS to GAE is usually not that easy and quick at least for a simple rails app deployment using Postgres.

Appengine has still less developers community which is why learning curve is high and you need to dig and troubleshoot more than AWS which is abundant with tutorials, gems, plugins etc.