We all know that the recommended settings are VH/M, but I didn't like the game so much like that. It's been said a thousand times: it's no fun fighting several stacks per turn.
I usually play H/M, but I set it at H/H in my last Romani campaign, and it was a blast. I found it to be a really good balance. Usually on Medium battle difficulty, units rout a bit too easily for my tastes. On Hard settings routs could still happen if timed well, but the enemy was much more resilient. Battles were longer and more bitter, and I actually lost sometimes.
So my new favorite settings are H/H. Share yours.