All of Planescape has it to a certain degree, but some factions highlight it more heavily than others. Transcendent Order, Society of Sensation, Dustmen, etc.

The Xaositects have a lot of their philosophy rooted in Cynicism. This gets a direct reference in Torment with Starved Dog Barking. That isn’t to say there isn’t something of other philosophies there (discordianism, Buddhism, etc).

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEoh, wait, I should buy the game first.

…done. Thanks! Now, where was I? Oh, right.

EEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE…!

That remake came out. http://www.planescape.com/ I am so excited that it is now available for tablets!

Not just them (though the Dusties are sorta Theravada Buddhism without the compassion). There’s a very Zen feel to the Xaositects, too.

Man, last time I played Planescape: Torment was as a teenager. Can’t wait for that remake to come out now that I’m an adult.

Pretty much all of the factions draw from different real-world philosophies. The Dustmen – as you note – draw a lot from Buddhism.