Given that the adventure guide doesn't show loot past mythic level, I always found it annoying to guess what stats an item for a specific dungeon/m level would drop. So over the past couple days I wrote an addon to do just that. It's called Mythic Plus Loot: https://www.curseforge.com/wow/addons/mythic-plus-loot

You can sort by armor type, item slot, and m level in order to see which dungeons you should target farm to fill a gear slot.

This project is open source and any suggestions are welcome. A couple things that will be added in the future that over the couple days of using it I've noticed: 1) adding a minimap button so the addon can be opened that way and 2) adding sorting by dungeon as well so you can see possible upgrades per dungeon instead of per item slot.

If you have any suggestions let me know!