Long time ago some JP guy posted a "tier list" for HELM NM difficulty and it was something like Schah > Erynis > Teles > Albumen >>>> Vinipata > Onychophora > Zerde.
After killing each NM at least 3 times (and many other failed attempts) my personal tier list is the following:
Onychophora > Vinipata > Schah > Teles > Albumen > Erynis > Zerde
My personal reasoning under spoiler. What's your tier list?
Onychophora has a somewhat high degree of randomness (stuff players can't control) compared to other NMs. Need to be watchful of the TP moves, of the casting, of the fire mode, need to do LV1 SCs only, need to do 5 different ones in a sequence, etc etc. I dunno, I find it the most annoying of the bunch.
Vinipata is easier since when we started using Albumen's strat (BRD+Breakga) on adds, but he's still annoying with his 2 stances, the 4th move to stun, and overall his damage is pretty high, definitely my second most hated.
Schah/Teles/Albumen are kinda close together, hard to set who comes first. Tempted to put Teles in front of Schah.
Albumen is very easy if you have a good BRD/BLM taking care of adds, but the hp down debuff can be dangerous at lower %, plus need to be very watchful/fast with the dispel thing.
Schah is, dunno, doesn't seem such a big deal? It's arguably hard at start but it gets easier and easier over time. With good practice and a good group it's not that bad? Maybe we've just been lucky I dunno, only killed it 4 times. (and 6 attempts iir?)
Teles instead ungh, it's not hard but let's say there's a lot of stuff you need to pay attention to. Its SP use, moves to stun, moves to get out of range from etc.
Erynis is incredibly easy (and boring) with the THF/SMN strategy, but putting Zerde last (even if it's arguably "harder" than Erynis) simply because it's a very fast fight, wether you win or wipe it's a few mins, making it less time consuming and hence easier to me.