IIRC, there was an Ektol developer, don't know if it's still available, only to pro labs, or if it's really Ektanol... my memory grows fuzzy.
I have some APX400 lying around, including one roll exposed in an Oly 35SP, and have ordered some more. I have both Rodinal & DDX, and while I love Rodinal, I have heard such good things about DDX that I planned to process the first roll of APX in DDX.
I have one roll of Agfapan processed in Rodinal 1:50 but with very minimal agitation and at 24C. The minimal agitation allows this dilute developer to give delicate highlight separation while maintaining reasonable grain. As mentioned, the grain of film developed in Rodinal is very sharp, yielding high acutance. In my mind, Rodinal provides the best balance of what I am looking for in a negative. But I have been away from darkroom work for so long that I need to reestablish my workflow. I currently have no printing facilities, so can only process the film and look at the negatives under a loupe.