I’ve seen a few posts asking about this in varying threads, so I’ll put this in one place. Keep in mind, the item levels have been changing a bit recently and are still subject to change.
Crafting
L60 blues (151 item level)
L60 upgraded blues (168 item level, requires a revered reputation to make)
Covenant Armor
This is gear that can be upgraded up to item level 197. It requires progress in the covenant campaign and anima.
PvP
Starting honor gear (158 item level)
Fully upgraded honor gear (190 item level, requires a prohibitive amount of honor for a full set)
Starting conquest gear (190 item level)
Fully upgraded conquest gear (unknown, requirements unknown)
Dungeons
Normal (157 item level)
Heroic (170 item level)
Mythic 0 (183 item level)
Mythic+ End of Dungeon Chest (187 for m2 up to 210 for m15)
Only one reward per dungeon. In other words, only one person gets loot.
Raids
LFR (187/194 item level)
Normal (200/207 item level)
Heroic (213/220 item level)
Mythic (226/233 item level)
Weekly Vault
Raids (item level depends on raid difficulty)
Mythic+ (200 for m2 up to 226 for m14)
Conquest (item level depends on rating)
World Quests
These seem to scale with your renown level and item level and are fluctuating a lot. ATM, they are consistently giving 200 item level rewards (with 190 item level and 40 renown).
Covenant Callings (similar to Emissaries)
These have an RNG chance to reward gear. The highest reward I have seen so far is 203 item level.
World Bosses
These give 207 item level gear.
Torghast
Unknown - this has been dropping placeholders instead of loot, but I haven’t done it recently.
Dungeon Bonus Event
Completing four mythics gives a 213 item level reward.
Let me know if you have further information I can add or corrections that need to be made. I’ll keep this updated if changes are made to the systems.