Well, first you should note that the 5s ladder has been removed. :3

Of those classes DKs and Pallies and hunters (if you wish to just run one class) would be able to clear mythic+ instances to atleast some extent. The best success currently has been found in stacking tanks. Mixed groups can as well, but anything non-tank is a lot more prone to dying to mechanics sadly.

As far a PVP... I honestly don't know what would work for 3s, as I've not tried a single one yet. Apart from seeing how far you can climb the ladder there simply is nothing to gain from it anymore. The gear I get from world quests, LFR, world bosses and the occasional mythic is already better since actual PVP gear was removed.

Quote Originally Posted by Dinosawrex View Post
Not sure, but i dont think you can multibox in PvP anymore since they removed /Follow in bgs atleast.
This change only affected random battlegrounds. Follow works (or atleast used to, not tried in legion) fine in rated BGs and Arena.