I'm still a big fan of the Michelin S12 on the rear (usually partnered with an MH3 on the front). I know its supposed to be a soft-terrain tyre, but they grip well on everything and hold up fairly well on rocks.
I ended up with a MH3 rear on my 06 YZ, and it has impressed me too.
Edges seem to matter more on a 19, compared to an 18, FWIW.