What program do you use to mock out architecture diagrams?

I am designing a rather complicated architecture, and am looking for a tool that will make it easy to explain how data gets routed through the system. Like this from AWS –

https://d1.awsstatic.com/architecture-diagrams/ArchitectureDiagrams/aws-industrial-PdM-ML-storage-RA.pdf

Is there an app or should I just use something like Sketch?