Personally, I'd do
Will -> Zorlok -> Amber-Shaper -> Grand-Empress -> Protectors -> Lei-Shi -> Tsulong -> Sha
But then again, without the right strategies or setup, these first 3 can be harder than Lei-Shi. Plus, Will and Zorlok don't drop very valuable loot. No tokens, no weapons.
The kills that would help your guild the most right now are Lei-Shi and Tsulong HC, because they drop BiS-weapons. Unless you want to try the Tsulong exploit, Lei-Shi is the easier of the two. However, you're very close to the enrage on Garalon which means your DPS is not all that good. Lei-Shi is definately possible with your dps but you can't mess up the stacks and you need to end hide quickly or you'll hit the enrage. Good luck whichever way you go
Regards