Just left Google after ~4 years, and couldn't be happier (always been more comfortable independent though). I liked everyone I worked with, but the work was incremental at best, and most often about perf optics. You'll probably be surprised how hard people work outside those companies, and how good they are (even if you already knew -- it's easy to forget in there). I'd say if you don't have something you really want…
I've found once most companies reach a certain size, from an employee perspective they become less results-driven and more perf optics driven.