The Newfys are a much easier draw, but hunting the California sub-species of Rocky Mountain Bighorns, is always a step down in horn size. They are still Rocky Mt Sheep and there are plenty of good Cali rams on that mountain.
I'd say your decision depends on how soon you want to draw. No doubt the Green River sheep get most of the attention in Utah, but any sheep hunt is a true adventure, especially if you are willing to make it so.
There are 300 sheep on the Newfys right now. They took 9 (almost all ewes) off the mountain yesterday to supplement the New Oak Creek herd. I volunteered Saturday but the turbulent weather wouldn't allow flying so they didn't get any sheep. They were hoping to take 30 more off, but will have to wait until next year.
Good luck on the draws regardless of where you put in.