Microdol-X 1:3 was my mainstay with Tri-X film at ASA 400. Fine crisp grain. Today's TMax 100 in D-76 1:1 seems to be very roughly the same (I have not made a rigorous comparison), though ISO 100. I'd like to find a really fine grain easily obtainable developer for TMax 100 or Ilford 100 or Fuji 50. I'll have to try Microphen, I think. Ultimately I'd like to get the finest grain I can in 120 film size for anything at ISO 12 or above.