Currently updated for The Eternal Palace & Mechagon.
Will is listed as Best In Slot Redux in-game.

The BiS Manager is where all the magic happens.

This is the place where you can set your BestInSlot lists. On startup, the AddOn automatically selects the highest available raid tier and difficulty. You can make a BestInSlot list for every raid tier, for every difficulty, for every specialization. For instance, a hunter can have 3 specializations for Mythic Antorus, the Burning Throne: one for Beast Mastery, Marksmanship, and Survival.

The manager will show you a copy of your inventory screen and for each slot, you can set a BestInSlot item. The AddOn uses the loot list of that list and checks if you're eligible for that loot in that slot. You'll get a list with items that you're eligible to roll for the selected raid tier, difficulty and specialization.

This addon also has a guild feature that lets you request other custom lists, e.g; your whole raid roster to see how far everyone one is from full bis and if one boss is about to become just a waste of time since it doesn't grant any gear gain. This then makes it easier for officers to get a better understanding of where to distribute loot and to whom.

Personal Note: This addon was mainly brought back for my own personal use to help our guildies and manage the roster. <Eriks Raidingskola> <3

This is a recompiled version of the original addon along with contributions from commenters on the original addon page.

This is not mine and I don't own anything from it, all credit goes to:
https://www.curseforge.com/wow/addons/bestinslotredux/

Razhints BIS-lista