1) What is the best alternative to Angular?
2) What should developers invest their resources and time in?
For 1), like drinchev says, it heavily depends on your usecase. If you're making a 'regular' website i would opt for plain old backend HTML rendering combined with simple Javascript and maybe a bit of jQuery. But if you're making a 'webapp' that's very dynamic, a framework like Angular or React might be a better option.
Considering question 2): invest your time in learning Javascript, and whatever language you think might be useful. It's good to know as many frameworks as possible, but in the end language knowledge is far more useful than framework-specific knowledge.