Modernism: Wim Crouwel, Josef Müller-Brockman, Massimo Vignelli.
I think most designers should have the knowledge and ability to create and design on a nicely resolved grid system, and because Modernist work is structured on a geometric grid, is has a classic, timeless feel.
If you need proof of this, go to a library and look at any graphic design annual from the late 1980s to early 1990s; the work that clearly stands up to today’s standards is that which is grid-based. Most movements will come and go, but I think Modernism will be
acceptable for the duration.

If you’re looking for examples of a contemporary studio focusing on
the Modernist style, check out Amsterdam-based Experimental Jetset; the blog AisleOne is a worthwhile Modernist resource as well.