I'm a fan of Noodler's Kung Te-Cheng. Great colour as it is or diluted and great performance on cheap paper. Gosh darn permanent too. I am, however, not blind to its mischievous character. I posted here before asking if anyone's tried it on a TWSBI. I ended up passing because I was (am still) thinking of selling the pen further down the road.
I've used it on some pens with no problems. The nib dries up if you don't use it for a week, but a 10 second rinse under a tap and it's good to go. There are, of course, some pens where it doesn't work. It kept clogging my Metro and I unimaginatively used it on a 78G. Ink turned to sludge. What pens do you use with KTC?