My fave combo is Kodak Tmax100 pulled down to 50 or 25 and developed in Patterson FX39 ,,very very high acutance and edge sharpness. This is also a VERY forgiving developer and can also be used as a compensating developer for very high contrast situations.
I Use others such as ID11 . Microphen etc ,, I have even used coffee
Way back in the hay day of film I could make up to 2 doz different developers at any given time and would use around 1 doz different films.
Now due to limited availability I use one film (Tmax100) and one developer ( FX39 )
B&w films I've tried are Agfa APX, Efke, Kodak Plus-X, Tri-X, T-Max 100, T-Max 400, Ilford Delta 100, Blue Fire, Micro Copex Imagelink and Rollei Ortho 25. I also used Kodak infrared, back when they still had that.
Developers I've used are D76, Microdol-X, Rodinal, T-Max, a special developer for the Imagelink and a few others. These are the four I use most.
Films: Agfa APX 25 was my favorite film, but it was discontinued. Since then I mostly use Efke. Efke KB25, you are already familliar with. Rollei Ortho 25, is really good, but it's more expensive than Efke here and there is not a huge advantage to using it. I only use Rollei when it is for something special, like for a show. Kodak Plus-X is just a good basic film. If you like a thick emulsion, this is the one for you. Tri-X is the most foolproof. It is a very forgiving film. It does not have a fine grain though, so this is a consideration. T-Max 100 and T-Max 400 are what I use for grain effects. They are very sensitive to pretty much everything to do with development. You can be really anal and gentle about your development and get nearly invisible grain or you can do everything "wrong" and get grain from hell. With diluted D76, agitated like hell, your photos will come out looking like a pointillist painting. This can be a good thing if you plan for it: [link] Ilford Delta 100 I have a problem with this film. I have been developing it in D76 and it never seems to have enough contrast even when pushed two stops. Maybe I need to try it with another developer. Blue Fire was a disappointment. It isn't any better than anything else, and it isn't as good as some that cost less. It supposedly requires a special developer but I think the "special" developer is just Rodinol; I can't see any difference if I do use Rodinol. Micro Copex Imagelink has been discontinued, I think. I have not seen any notices, but I can't find it anywhere. It was a pretty decent slow film, but it was a pain to develop it.
I'll have to try that combination. One other thing I noticed about Ilford Delta films: They can reticulate if the temperature drops during any stage of development, so you really need to watch your temperatures. It's the only film I have seen do that. The emulsion cracks up like a dry lake bed.
Now about the developers: D76 is just a good basic developer. With most films, it is the most foolproof. If you use it with T-Max and agitate it hard, you can use it to get coarse grain (if you want coarse grain). Without the extreme agitation, it gives you a fairly fine grain though. It is very good with Plus-X and Tri-X. Rodinol is good with Blue Fire, but otherwise gives you a coarser grain with most films. Microdol-X is a very fine grain developer, but it doesn't give you much contrast. If you push it a little, it works pretty well with Efke. You do have to push it a bit to get good contrast though. T-Max developer is the best developer for T-Max and b&w infrared film, if you are trying to get the finest possible grain from those films.
Thank you for sharing your knowledge. I just started to mix my own developer. Since I don't yet have a precise scale i used teaspoons for measurement. I know I wrong with that, but till I receive my scale it would have to do. Anyway I was surprised that even if I used a imprecise measurement for the components the film developed quite well. Well I had less grain and more detail in rodinal. So i'm curious how precise one must be in measuring the chemicals?