Piano only...

Also Thelonious Alone in San Francisco and Jessica Williams' All Alone

I have heard neither of these, but have heard enough good things about them (and, of course, have heard their other, non-solo recordings) that I plan to get them myself soon.

Brad Mehldau, Live in Tokyo (or something close to that title)

Also Mehldau's Elegiac Cycle, which I think is even better. As I recall, this has a few tunes with bass and drums, but is definitely mostly solo piano.

Seconding Pragmatist on Art Tatum, yes, Evans also