BiS isn't possible but, setting aside whatever awesome titanforges you might be sitting on, here are some general guidelines based on generally wanting to maximize haste/mastery.
Things that you'll definitely want:
Tarnished Sentinel - Trinket - Drops from Sisters of the Moon
Tier Legs - They have both haste and mastery
During progression if you have a choice you probably want to use the mythic Goroth chest (heavy haste, light mastery) over tier chest (heavy crit, light mastery).
You probably want to use offset shoulders as well. Tier is crit/vers (heavier vers than crit), the non-tier option is haste/mastery, slightly heavier haste than mastery.
If you go with Helm, Back, Legs, Gloves you guarantee yourself at least one of haste or mastery in every slot and your two off pieces will come from early into mythic progression (goroth and harjatan) and both be haste/mastery.
None of the ToS necks are good for moonkin. So hopefully you have a nice one from somewhere else. One is heavy haste, light vers. The other is a pretty even mastery/crit split. They'll be very close in value.
Kiljaeden has a nice belt, haste/mastery, slightly heavier mastery, which is +5 ilvl so should hold up nicely through mythic progression.
Boot choices aren't great—another good place to target M+ or hope for a previous nice titanforge. You've got a light haste, heavy crit pair of boots from Harjatan or a light mastery, heavy vers pair from Fallen Avatar.
The nicest ring is from Harjatan, pretty even Haste/Mastery split, slightly heavy to mastery. Again, an earlyish boss so you should be nicely set up for mythic progression by pairing it with either IFE or SotA.
Arcane Relics: (+ or - means relative to standard difficulty, so -5 is 915 on heroic, +5 is 925 on heroic, 0, is 920 on heroic)
-5, Falling Star, from Demonic INquisition
-5, Sunfire Burns, from Goroth
0, Solar Stabbing, from Sisters of the moon
+5, Light of the Evening Star, Kiljaeden
Life Relics:
-5, Falling Star, Goroth
0, Sunfire Burns, Sisters of the Moon
0, Darkside of the Moon, Desolate Host
0, Scythe of the Stars, Fallen Avatar
You'll have to choose how you want to play for relic choice. If you want to go all in on Starfall, get 3x Falling Star. If you want to go more well rounded, I'd get 1x Scythe, 1x Solar Stabbing, 1xSunfire Burns. If you want to go all in on single target, go 2x Solar Stabing, 1xScythe.
So, TL;DR
1. The only trinket you really want out of ToS is the Tarnished Sentinel. Hopefully you have a nice Whispers.
2. For tier, focusing on being set up well for mythic progression and trying to maximize haste/mastery, I'd want shoulder (Harjatan) and chest (Goroth) off pieces (mythic) to pair with the other tier slots.
3. I'd hope for boots from M+/weekly cache, some other lucky titan forge.
4. Same for necks.
5. For wrist, also not a great slot for us. Luckily we're probably running OI here anyway.
6. For rings, there's only one good ring, from Harjatan. Otherwise you hopefully get something usable out of a cache or already have a nice titanforge. If you're not running SotA+IFE but just one of the two legendary rings, this will probably be the best value ring in the instance.
7. For waist, you want KJ's belt.
8. For relics, a lot of flexibility here. Your choice.