For example, I like using Xtol because it gives extreme shadow detail at 1:1 dilution. This is perfect for push processing when I need more speed from the film I have at hand.
It works very well as a replenished system for film shot at normal speed (loses 1/2 stop film speed / shadow detail compared to stock), and the convenience is that it's a developer where the replenisher and the developer is the same solution. It's a powder, which means that when I order it, shipping cost is low, and it's a good way to reduce carbon emissions from shipping. As a powder, I can order 50 bags and store them for years or decades before I use them, so they store well. So, to me this is a better solution than any of the other developers.
D76 is great because it's a developer that has literally a metric shedload of information available on it. Any photography teacher that has dealt with darkroom will know how to use it and help out. Plus, it's a fine solvent developer that gives results that nobody can really argue with. A fine powder developer that has the convenience of being available in small packets for low volume processing, mixing a quart at a time. D76-R used to be available for replenishing, but isn't anymore. I believe you can mix your own, if you're into that sort of thing and have the appropriate equipment.
HC-110 - liquid concentrate with high flexibility in varying dilutions. Longer developing time = more shadow detail, which is what you get when you dilute it a lot. Lasts forever and is easy to mix. Moderately fine grain and normal film speed. Inexpensive. Used to have a replenishing solution available, but from what I understand it's possible to replenish using just the developer. Not sure how to do it, and if it's stable in the long term like Xtol is.
TMax and TMax RS - liquid concentrate with qualities similar to Xtol, but with a 'brighter' tonality, meaning a little bit more punch to the highlights. Also has slightly larger grain, but has the same wonderful film speed abilities. Can be replenished (even the regular TMax).
Basically, you find what you like and run with it. If you're getting good results with HC-110 - exactly why do you want to switch to something else? Is there a specific reason? For example, if you want more shadow detail, and a developer that's generally recommended to give better results in push processing, Xtol or TMax would be a better choice. If you want finer grain and sharper negs, Xtol is a good choice. Etc.
But in the end, like you suggest yourself, the differences aren't that great, and the end result of great prints depend a lot more on how you use your developer, than what materials you use.