I recently passed the AWS Certified Solutions Architect exam. I used acloud.guru to study mostly. Not only are their focused learning tracks based on the different exams (Solutions, Security, Big Data etc.) but there are also more in-depth tutorials for specific services and architectures.

It's a bit pricey at $39.99 a month, but I think for the quality of the courses and the overall number of courses, I think it's worth it

Disclaimer: I am in no way affiliated with acloud.guru