Making Technology Choices for Personal Growth.

When I started doing IT as a profession, the number of available, commercially used technologies was considerably less. Back then, most of IT ran on IBM mainframes. The number of tools you needed to learn to be marketable could be counted on one or two hands.  Today, there are far too many technologies/products/frameworks and not nearly enough time to learn them all.  Should I invest in AngularJS or React? Java8 or Scala? Amazon or Azure? Python or Node.js?  The list goes on an...