I recently attended the London AWSome day (Jan 2016) focussed around the Amazon Web Services platform. As someone who has specialised in Azure for the last few years I think its important to try and keep a broader mindset when it comes to cloud providers (suitably embarrassed that this was my first foray into AWS!).
Its worth remembering that you should try and focus on the cloud architecture and associated patterns/best practices they are of course technology agnostic so equally applicable no matter the technology provider.
The event was really a 101 introduction to AWS so I'm not going to even try to compare the two platforms service by service (others have tried to do that already) however there were some interesting points I took away from the event.
Let me re-iterate, these are a few points that stood out for me personally and it is not meant to be an exhaustive comparison of the respective platforms.
AWS console vs Azure portal(s)
The AWS console definitely looks a little bit dated compared to Azure portals (in particular the new portal). However the important aspect of the console/portal should not just be the aesthetics but also the performance and usability, so will be interesting to compare that aspect of the portals when I get a chance.
EC2 spot instances
I really liked the idea of being able to specify a price ("bid") for compute that you were willing to pay and have compute switched on when you hit that bid price. If you have workloads which can use such sporadic compute availability (admittedly not the most common use case) then EC2 spot instances are an interesting idea and Azure doesn't have anything similar.
AWS lambda is a very interesting feature, in a nutshell it allows "serverless" processing of code. Looking at Azure I can't quite see a parallel service, the closest is probably Azure webjobs which can run code (scripts or exe) in Azure App Service Web Apps (a PaaS feature so no need to manage VMs directly).
This is one area where Azure does seem to be further long compared to AWS. Both AWS and Azure offer infrastructure level hybrid connectivity through dedicated connections (Azure ExpressRoute and AWS Direct Connect) and both support various VPN options however AWS doesn't offer the same level of PaaS hybrid connectivity such as Azure Hybrid connections and the new Azure Stack is likely to increase that gap.
Billing for compute
AWS bills per hour for compute compared to per minute billing with Azure. This doesn't sound like a big deal on the grant scheme of things however this could translate to significant cost differences if you are using the expensive tiers of compute for short periods of time.
I know I've not even scratched the surface of either cloud platform in this post and I wasn't intending to, rather I wanted to brain dump some of my thoughts on what I did see of the AWS platform and the natural comparisons that one would draw coming from an Azure background.
Both cloud platforms are leaders in the Gartner magic quadrant for cloud IaaS and storage for good reason and deserve an indepth analysis if you are looking to choose between them. Feel free to get in touch if you'd like some input in that process.
p.s. I was really encouraged by the fact that throughout the day there was a strong emphasis on good architecture principles and security from the presenter/trainer (Tom Woodyer).