Try one hour stand developing with Rodinal ≈1:100 and Acros ISO 100, Efke 25, Rollei Pan 25, and Ilford PAN F+. All come out great. I like Efke and Rollei PAN but because of price I buy a lot of Acros 100. I haven't experimented much with Kodak TMAX. You can be pretty cavalier with Rodinal storage and it will last forever at full strength. You don't have to mix up and use liters of it. It is dirt cheap. For one hour stand developing I use 4 mL of Rodinal per a roll of 120 or 35mm. I put the 4 mL of Rodinal in whatever volume of distilled water is appropriate for what I'm developing. The beauty of it is you can develop Efke and Acros in the same tank at the same time. The dilution and time are the same for everything. I invert the tank very gently for 30 seconds at the beginning and then I just leave it alone for an hour. I use a water stop bath and then fix. Give it a try. Allegedly minimizing the agitation helps to reduce grain.
I did not have good results with this technique and 400 ISO film. 100 ISO or slower is beautiful with Rodinal stand.
That's interesting, I"ll have to give stand development a try. How does Acros 100 compare to TMAX 100 ?