Each developer has slightly or sometimes very unique characteristics. D76 is so popular because it does most things well, though none of them "best in class". ID-11 is for all purposes the same developer as D76. So most other developers can be described in relation to D76, e.g. more/less contrasty, better/worse shadow detail or film speed, finer/coarser grain etc. Some developer-film combinations behave out of character for either the film or the developer. In that instance, D76 and Xtol are good developers, as most modern films have been developed with them in mind and will yield good results. Rodinal is the easiest developer to make and by far the cheapest, but for some films it just doesn't work well (eg Kentmere 400). The same can be said for some of the Caffenol formulas (with eg TMax 400). There are many possibilities, and they can be overwhelming for a beginner. Therefore, I think the most pragmatic approach is to stick to one or two emulsions, let's say a fast and slow one, and to pick one developer to work with. Then only change when there is something that you want to achieve that is not possible with what you have.

The higher the alkalinity of your developer, the more the gelatine softens during development, AFAIK. So the best combination in my opinion depends on the developer you use. If you use a high-pH film developer such as Rodinal at low dilution, then it helps to use a hardening fixer. For mild developers like Xtol and D76 it may be unnecessary. I keep film and paper fixer apart, because that way it is easier to keep track of how far I have used it. I think many people use one batch for both film and paper with little to no ill effect. Try and see what works for you.

Rodinal is the only film developer that I know of that is also routinely applied to paper development. When diluted, it has poor keeping properties, and therefore has to be made fresh for each batch. There is an article on phenidone-ascorbate developers by Patrick Gainer on unblinking eye somewhere. Google it. Phenidone is available from the suppliers of alternative process chemicals, eg Photo Formulary, Bostik & Sullivan etc. One uses minute quantities of it, so even 10 grams go quite far. The rest of those formulas are prepared using washing soda, vitamin C etc. Those should be available from grocery stores and health food stores. I have tried using his developers for film, and have not liked the results but I may have had a bad batch of phenidone. But for paper they work quite nicely too.

If you are interested in making Rodinal from paracetamol (aka acetaminophen), let me know. It is easy and cheap, as in a few pence per film developed.