I've recently started teaching myself piano (via Bartok's Mikrokosmos) and feel it would be helpful to supplement the pieces with some standard exercises. Everyone I speak with suggests Czerny, but there are simply a ton of different books of his collected exercises; I'm not sure where the best place is to start. Is there one Czerny book that stands out as being particularly foundational?
I'd suggest not doing Czerny. A lot of people don't realize that the Czerny studies were written specifically as preparatory exercises for the Beethoven Sonatas. If you don't know which studies match up to which sonatas, you're not doing anyone any favors. Learn to play scales and common chord progressions. From there, I'd progress to Liszt, Dohnanyi, or Brahms technical studies. My preference is Liszt.