to me, Six Pianos is the most Reichian work by Reich.
Glass is more associated with electronic keyboards, and his work for solo piano (e.g. the album Solo Piano!) is pretty poor.
That's a matter of opinion.Glass piano works (particularly the pieces from the Solo Piano album such as Metamorphosis and Wichita Vortex Sutra) are regularly performed in concert halls all over the world. Hardly the calling card of works which are "pretty poor"...
Don't forget Phillip Aaberg and George Winston!
There's nothing wrong with a bit of Einaudi either. His music may be very samey but it's melodically very beautiful and often rather moving. Isn't that the point of music when all is said and done?
Should give a mention to Ann Southam's cycles of Glass Houses and Rivers. They are a significant body of work for solo piano. Southam passed away last year.