Tested some unique farming strats this weekend! I started out with Breach + Beyond in Dunes map, and while it did give me a lot of uniques, most of them were between t5 and t3, with a few t2, and rarely some t1s. It gave a lot of currency too, but maps took quite a while to clear (and loot, lol), even with my KBoC build. People in the SSF global chat (/global 773, very nice chat to be in even if you're not SSF) recently started discussing some Exile strat, which I decided to try. You run:
2x Anarchy Scarab of the Exceptional
1x Titanic Scarab
1x Titanic Scarab of Legends
1x Scarab of your choice (I run Domination Scarab)
You max out rarity, map effect and pack size on your atlas tree, and fully spec into Exiles (except for Rogue Trader, which makes them way too tanky and difficult).
You roll tier 16.5 maps (memory influenced) for ~150%+ item rarity and mods that won't make you just fall over and die. I run Haunted Mansion because the Mirage coverage is pretty good.
You hope for the Exceptional Exile to convert all of their loot to unique items, and then hope for t1s and t0s!
Mind you this strat is VERY rippy. Some maps you just get fucked over and there's a basically unkillable Exile (the Tornado Shot exile usually gives me trouble, or most of them with Soul Eater). In around 25-30 maps of this I've gotten 2 t0s (Bino's Kitchen Knife and Voltaxic Rift), no clue if that's lucky or not because there's only a few people running it in SSF global (and I don't check reddit so no clue if this is common knowledge), but almost all of those people have gotten multiple t0s.
Edit: The very next map after I made this post I run into this Exile, who I could not even get to 95% health. Since I'm a crit chaos build I deal basically negative damage to this guy