Everything is very balanced in the 39 bracket.
Other than Prot Warriors, everything is pretty balanced right now.
FCs have ton of survivability(IE: My FoL Crits only heal for 1/3 of a BiS FC's Health).
Healers aren't overpowered, but you most likely will struggle to 1v1 them.
DPS, other than prot warriors, are very balanced right now.
There's a large amount of different types of CCs and every class brings their own form of great utilities to this bracket.
I'm sure there are other classes that do more damage than others, but for the most part everything is very balanced.
Other than the Cloak of Coordination enchantments, Grandfathered gear really isn't gamebreaking at this level. But Skill > Gear in this bracket
From what I gathered, Alliance has been on a losing streak lately. But not by any means is this bracket one-sided. Both factions have some amazing players with dedicated FCs.
Rogues used to be a huge issue, but rogues aren't as bad as they used to be since they lost shadowstep and kidney shot.
Shadow Priests used to be a big big issue. But now that across-the-board, all DPS got a buff and shadow priests got a huge healing nerf(and most healers got a healing buff), Their Offhealing isn't as big of an issue anymore. Phantasm got nerfed and Psyfiend doesn't spam fear on the same target anymore(buff and a nerf at the same time).
As soon as Prot Warrior's Shield slam dmg gets nerfed, 39s will easily be the best bracket in the twinking community.