Modern web stack in 2015

New frameworks and libraries hit the market at a remarkable pace, while others adapt or slowly die.

Apache seems seriously challenged as nginx market share is growing. Previous giants like PHP and ASP.NET lose traction in favor of JS-based alternatives like Node.js, which will not scale gracefully on a single thread in the case of sudden bursts of user activity, and whose community just recently forked (http://ift.tt/1FPFJkw). jQuery remains a solid option but challengers like ReactJS have recently appeared.

So, from a purely technical standpoint, disregarding the open source/proprietary perspective: what stack would you use if you were to write a fast, scalable site with adaptive UI today? This includes web server, database, interface between front/back-end, front-end frameworks/philosophies and so on.