At university we only had ID-11, so for three years I didn't even realise that you could try different developers, duh!
After I left uni, I tried to find an easy alternative because I had never mixed a powder developer before and I was a bit worried about it, so I tried Rodinal, but I didn't like it that much.
I shoot a lot of Kodak Tri-X (120) and I develop it with HC110 (dilution B) or Diafine.
I have tried Ilford Ilfotec DD-X to push HP5 (120) to 1600 iso and I love it, but it's quite expensive.
Now I'm also using Microphen to develop sheets (5x4) of Foma 100.
I'd like to experiment more combinations, so I have got quite a few developers on my shelves, I'll probably update in the future