…is it better to run Nightmare rather than Ultimate, for the base range?
Or does the higher drop rate in Ultimate make it better?
Nightmare ?
If you want to farm legendary pieces of set, nemessis farm in elite is the place to go.
I guess it’s more a matter of character level (75+) than of the difficulty mode.
why elite ant not ultimate?
My guess would be that the same items drop from nemesis bosses regardless of difficulty but in ult they’re a lot harder, so you may as well kill the easier version for epics.
Ultimate is a lot harder than elite and need a lot of prepare to kill one. If you can kill in ultimate just keep doing it. At least you will feel like you’re farming in the most high chance drop rate.
Though, I think Elite nemesis is ok for farming. Farming comfortably fast & more run but less drop rate isn’t that bad and most time I didn’t get legendary it would dropped purple blueprint instead. Legendary drop is always random, you may get armor parts like hands or belt those have no set.
Ex. Tonight I killed 4 ultimate nemesis but get only 1 legendary and a purple recipe. 
PS. For 100% legendary drop farming. Clear 150th wave in Crucible DLC. Keep tribute points to re-enter at high wave then kill kill kill to finished.
For legendary Farming, Crucible Gladiator 150 is the way to go.
1 run = 6-10 legends. Then you can just repeat from 130 and get 4-5 legends.
For builds that can actually do that, you can check mine on http://www.grimdawn.com/forums/showthread.php?p=435832
There’s the legends drop on the end of the video if you wish to see the drops.
I run a Sab for farming.
So difficulty is not an issue. :rolleyes:
I was only asking about raw efficiency.
Ultimate is much more efficient than Elite and Gladiator Crucible is even more efficient.
Thank you. 
Ultimate is only more efficient if you can kill fast on Ultimate. If it takes you 30 seconds to kill Valadaran on Elite, but five minutes on Ultimate, I doubt that Ultimate farming will be more efficient in the long run.
Also, it would be nice if people would post some numbers (from the game’s source code or from their own experiments), to see what “much more efficient” or “better drop rates” actually means.
The OP said he has no problem killing in ultimate, hence my minimalistic post. As for nemeses you’ll be spending much more time looking for them than fighting them, regardless of difficulty. The only factor is if you genuinely struggle with them.