BiS is matrix cube and either 2pc rakata (which pieces will vary per class pending the armoring) or crafted belt & bracer (not rakata BTW) with main stat augments. Once you can pull the barrel/hilt from a T3 weapon, an orange craft with an augment slot will also be BiS. I've already min/maxed the hell out of my char and consistently get the 5k dmg medal in warzones, even on full BM players.
FYI the current problem with PVP gear, and hilariously creates the opposite of PVE players playing PVE for gear, is that expertise has a bad diminishing returns curve, so that BIS PVP gear is a mix of Battlemaster and Rakata. The PVP gear rebalance should fix the issue of having to do raids to optimize PVP gear as well. It's good for everyone!
The rebalance will do nothing for the situation of needing to raid because of the set bonuses, though.