Thanks everyone for all of your input.
Looks like I'll just have to experiment, I have a number of the films listed already with more coming.
There was reference to Microdol-X. I think it's gone too, but I believe Ilford has a similar developer still in production. I hope formulas for the extinct developers become available so at least we can make our own.
One comment too if I may. Remember that much of what we do is subjective and a matter of taste. Some (as has been demonstated on this forum) love grain, the more the better, while others do not. So, if one is asking about a substitute, you would logically look toward a product that would have a similar appearance or properties. As an example; I lean toward warmer papers. In some cases, more brown than black. I'm not sure that anything like that even exists anymore. Can you guess what my next posting might be?
Now, I wonder if those 2 bulk roll of High Contrast Copy Film in the freezer are still good?