A modern programming language that makes developers happier.

kotlinlang

If you like to hear yet another opinion, here is mine.
I don't like all his hype for MVVVV stuff these days, I prefer to write simpler (or better said: with one layer of abstraction less) code, extract and unit test logic if it's complex (e.g. data transformations coming from different sources) and test most of the code with UI tests. When view code gets too complicated to keep it in Activity, I do composition, but I don't change tests to test components. UI tests never break when I do that. If they do, refactoring introduced a bug.