I use black a lot! I have found that it changes yearly as to who has the best black. One year it was Kona solids, but only that one year...then it was Michael Miller JET... Kaufman had a good one...
I generally tend to go back to the MM JET....

what is your favorite black to use?

Kona works well for me:)

MM JET for me, too.

have you found the Kona to much thinner these days?

I like Kona. Just like the look and feel of it. I have a stockpile of it so I don't know if the new ones are thinner.

Maywood Studios Black Magic. Double dyed, non-bleed. True black hole black, MUCH better than Kona.

don't believe I have tried Maywood...will have to look that up and try a yard...

My LQS owner told me about it, and it is truly luscious! She really disparages Kona compared to it. She won't carry Kona, doesn't like it! LOL. The day I got it, someone bought a whole bolt for themselves.

Moda

I buy it by the bolt myself...