Azure, AWS, and GCP have been around for quite a while and are quite similar to each other. They have very similar price structures, and very few differences in the services they all offer. The first thing you should consider when you wish to choose one of these is to choose the one that offers the services that you wish to use and the price differences between those services if they are being offered by multiple platforms. You might also need to look at community support developer documentation ease of use, maturity of the platform and the service, market adoption, etc.
AWS has been around for quite a long period of time than Azure and GCP, so it is definitely more mature. Although both GCP and Azure are catching up in terms of the services they offer. In the end, the major differences between these platforms emerge in their pricing and the services that they offer.
If you need help mastering Azure skills to the most advanced level, consider enrolling in Azure Course to help you achieve your goal.
You can also take a look at this end-to-end certification course which will teach you the basics of Azure or if you are just a beginner and wish to get your feet wet you can watch these end-to-end AWS tutorials.