Microsoft++
Although, maybe, I am obligated to be loyal to AWS for various reasons (my work is AWS-centric, plus the fact that it facilitated my foray in the cloud), but still, over the short span of time that I have been in this field -- I am getting increasingly impressed with Microsoft. Their documentation on aspects like cloud design patterns, microservices, etc., is simply impeccable -- to say the least!
Moreover, since I am a huge fan of MOOC websites like Coursera, edX, etc, not very long ago, I came across a very nice course on edX, being offered by Microsoft, called Architecting Distributed Cloud Applications, which, again, I loved!
Apart from cloud-specific courses, they have a lot of other, general CS courses in the offing, which are also pretty good.
Overall, I think MS has come of age under Mr. Nadela, and is delivering how it should. Kudos to the teams, who keep such useful artefacts updated, as well as open to the world.
After all, the age of silos is long gone, and collaboration is the key!