Should I focus first in AWS than Azure? My big company now provides us free enterprise subscription 150 dollars monthly credit to experiment.

Which one are you more likely to use straight away?
Go with that one.

They both offer similar features, and some things are better to setup on one vs the other, mind you that's dependant on what you will actually use as well.

Azure integrates well with anything .NET (obviously..), so if that's your primary framework then the choice is easy. That said, we are a .NET shop running everything in AWS - go figure..

Someone NOT involved in coding made that decision.

@C0D4 answer is AWS. I have little hands on experience with Azure and none with AWS. I think I will not go wrong choosing either of them as they are highly in demand skills in my area.