Wanting to move away from blacks is how I eventually came to the first of my three main inks, which is also from Diamine: Saddle Brown. I found that I still wanted something that wasn't too attention grabbing and was still dark enough to provide good contrast on nearly anything, but at the same time it's still far more interesting than the range of "permanent marker black" to "washed out black" that I was trying to enjoy before.

I hope you find something that works for you!