Ilford`s times are perfect for me if I print with a diffusion enlarger and #2 paper or filter.
Subtract 10% for condenser times. I use a standardised test target with detailed highlights and textured shadows and fine details which I light with studio strobes. So the target is always the same for initial calibration, summer, winter, night, or day. I have been using parts of it for 50 years and it always works.
My thermometers are calibrated and checked, clocks are correct, water is standard Chicago tap filtered. Agitation is exactly what Ilford recommends and developer is fresh.
It always works. Kodaks times are perfect also. What is way off is the massive development chart.
Now here is what you do after satisying the above and actually printing the test negs so you get detailed blacks and textured highlights. If your best time is 10% longer than Ilfords, when you change to a different Ilford developer, simply start with the 10 % correction as first step. Always print with no maniputation.
DDX is excellent if fresh and nothing except that and Xtol work well with Delta 400. Problem is the dates are coded and you don`t know what you are buying. It does not change color when it goes bad. There is no home method to test it except methods that do not work 100%, only partially.
There are no great differences in developers, only conviences. Just use ID11 or D76 and be happy. Pretty much the grain is built in and developers change it little. Concentrate on learning control and taking great pics. You will be better off. Really