I would recommend Burtgang like JonBigwood said.
then I would recommend body piece and maybe pant or ring.

from what you said you guy have T6 and 7 on farm. so you can wait for Pant to drop from T7 if you want to.

after this, I recommend you decide which BiS you want to go for, PARRY or DET/CRIT and then buy the SoL gear for your BIS. (make sure you maintain healthy amount of ACC tho, you would need 515 for T9 as MT)

I donno how far are you in T8 so you might wanna hold off buying SoL shield. unless you really want tower shield.