I can answer this. I am a scanning professional and have done tests on all the modern films and about 20-30 different developers. I did these tests on an Aztek Premier drum scanner, one of the top drum scanners, with exceptional resolution. I use a Jobo and primarily large format film. There are people that get differing results but there are some clear winners. First, the important thing is to define what makes a good negative to scan with. This is a negative that is smooth, or with as little grain as possible. This means that the grains are as densely packed together as the film will allow, as close to the original manufacture for the size of grains, or to be more specific, grain clumps.
There are many developers that make the grain smaller than need be. One of the infuriating, and Orwellian" things is that "fine-grained" developers are the exact opposite of fine grained. They contains solvents which dissolve the edges of the grain clumps a bit and as a result the grains are indeed smaller, but the are farther apart, making your print more grainy. Developers that are "over-active" can also damage the grain.
The three commercially available developers that seem to do the least bit of damage to grains are Xtol, PyroCat HD and the many forms of Pyrogallol, PMK, Rollo Pyro, etc. They are a major improvement over developers like D-76 and Rodinal. There are some other good ones, Perceptol, for instance, but they have other issues when dealing with large format film, like exhaustion. It isn't impossible to make a good developer as long as you keep the activation down, as well as go very easy on the solvent. However, PyroCat HD in Glycol is terrific, and so is Xtol.
Choosing a film is the obvious next part of this. T-Grained films have smaller grains, and are therefore better for scanning. I used to think that the newer films weren't as sensitive, but I was incorrect. I set up a test to specifically address this. All of the top films are excellent. My latest tests included Ilford's Delta 100, TMax, TMY2 and Efke 25. They were all good. I had previously thought that the modern films weren't as sensitive, but I was wrong. When I got the development spot on, they all excelled. Other than TMY2, the 400 speed films were not in the same class. Cheap, junky film (no names here) did not yield good results. I have settled on Delta because I like Ilford.
The one obvious mistake you can make is to over-develop the film, in any developer. As you blow out the highlights, the size of grain increases, especially with Xtol. I develop to a higher density than a silver negative, about 1.5 at the top.
The last thing I would say is that if you are going to only 14 inches in the print, you have a lot more choices than if you go to 20 or 30. If you print very contrasty, ignore these recommendations and do whatever you want - it doesn't matter. However, these are the basics, the results of a very carefully done series of tests.
