First you must decide what you want from your photographs. Then you pick a film that closely matches that idea. Then you pick a developer that gives similar qualities to the film you chose and try that out, by processing film and printing, and repeat until you have reliable results of what you can accomplish.
Most film/developer combinations can be made to work wonderfully. It matters more how you use your materials than what you use, so technique will have far bigger impact on things like tonality than your materials will.
So, there is no 'best'. Only what works for you. And you must do due diligence to find out what that is.
I'd probably opine that based on my experience and use, Ilfotec DD-X is Ilford's best all-round developer. It does nothing wrong and a lot of things exceedingly well. It's a great place to start. ID-11 1+1 is also a really great place to start.
Then if you want finer grain you can try Perceptol. But it will cost you film speed and some sharpness (in my experience). Or if you want very sharp negatives you could use Ilfosol-S, but then you'd lose film speed and you'd have more grain.
Nothing is for free, some new quality gained is almost always at the expense of something else - which is why I said at the beginning that you decide first what you want, and then you try to find a way to get what you want. Be specific and once you decide on a film and a developer, stay with it for a while to fully explore the possibilities and the limitations.