Generally speaking, however, Ilford's published developing times has given weak contrast, which is why a lot of people recommend to develop the film for one stop more underexposure than what you shot it at. So if you shoot it at 1600, you develop as if it was shot at 3200, etc. That gives more contrast.
But you may not like that, so this is why most of us will recommend that you do some testing first, to see what gives you the best results. This is very common in film photography. There are lots of variations in things like metering technique, light quality, shutter accuracy, even things like water quality mixed with the chemicals, summarized as 'local variations'. All these things matter and impact your results, which is why testing is required if you want optimal results.
It's easy to do. Shoot a roll with the camera on a tripod. Meter the light at some location, and burn off a few frames, bracketed at 800, 1000, 1250, 1600, 2000, 2500, and 3200. Develop to the median 1600 time and see how you're doing in the shadow detail department. Now shoot a second roll at that preferred speed, and have 1/3 of the roll developed at a time. If your first roll, where you found your preferred speed for shadow detail, seemed a little weak in contrast at that exposure index, the film should be developed longer. It the highlights were blocked up, it should be developed for less time. Adjust as necessary until you have a good compromise that gives you the results you want and need. There are no free rides here, unfortunately.
By using other people's recommendations you will get what works for them, and that may not necessarily work for you, because of the above mentioned 'local variations'.
But to re-emphasize what I said before, to begin, start shooting at 1600 and develop in any developer that Ilford recommends as if it was shot at 3200, and usually that gives you at least a good starting point. I have done this with Kodak Xtol, Kodak HC-110, Ilfotec DD-X, and Agfa Rodinal. All with results that worked well for me.
Attached picture is 35mm Delta 3200 shot at 1600 and developed in Rodinal 1+25. It is a negative scan so grain is a bit more pronounced than it would be in a print, and not as sharp.