Microdol-X, usually with TMax-100, is my standard developer. With TMX it produces grain as fine as TechPan, though TMX can't achieve the same 'large-format look' as TechPan. TechPan has very high resolution of very low contrast details, something it seems no other film can quite match - off my TP soap box, back to M-X...
M-X, in my experience, provides finer grain than Xtol or D-76 when used with very fine grain films. I often use it with Tri-X usually because I always have some M-X on hand, but for higher speed films Xtol works better and D-76 1:1 works far better than M-X with Plus-X.
I have tried DIY Microdol but find it is much more active than the Kodak product. I have just gone back to the Great Yellow Father and render the $.65 a roll, after spending a day shooting off a roll of film I would rather have reliable results.
I will brew my own paper developers - if I screw it up I can always do it over. With film there is less forgiveness for error.