Favorite late 20th/21st century composers?

...what?

You mean more modern composers?

I always liked John Cage

John Adams - Harmonielehre one of my favorites

Gustav Holst - The Planets was 1914-1916

I'm not big into Classical. I just had to pass the class. And I guess I just scratched the surface.

I've attended several John Cage "performances" and enjoyed them immensely. But I'm also highly into experimental stuff.

Darker and more emotive is a difficult one: a lot of late twentieth century classical music is sensationally dark, in the sense of being highly dissonant, but it is not necessarily emotionally expressive (emotional expression being one of the hallmarks of Romanticism, which became very much out of fashion). When people go for emotional expression, for example, they often run to Elgar's Cello Concerto, Rachmaninoff's Second & Third Piano Concertos or Barber's Adagio for Strings. None of these works is typically twentieth century.

A number of operas are very dark and expressive - Berg's Wozzeck, Bartok's Duke Bluebeard's Castle, Britten's Turn of the Screw and Shostakovich's Lady Macbeth of Mtsensk District - although opera is not to everyone's taste. Otherwise, there's really a load of works you could consider: Bartok's Music for Strings, Percussion & Celesta, Shostakovich's 8th String Quartet, Ligeti's Lux Aeterna, Pendecki's Threnody for the Victims of Hiroshima ... really, too many to start listing. You'd have more of a battle to find music that is cheerful.

If you are interested in emotive (kind of sad, reflective) as it can be presented in a minimalist sense, you should check out Arvo Pärt.  He's an Estonian composer who's works take from sacred music but are very much in the modern Scandinavian aesthetic.  I would start with 'Spiegel im Spiegel' for violin or cello and piano.

I'm not sure this is classical, but it's good stuff

Johann Johannson and Danny Elfman are both dark/emotive composers