From an objective marketing standpoint, both names are probably bad.
Nier is a fantasy word (?), a single syllable and there are no "sharp" letters (I don't know the exact term; something like s or t), this all makes it hard to remember for Westerners. But it has the second half "Automata" which definitely helps a bit.
Nioh is a japanese word (?) and hard to remember as well. Also, at least I sometimes got it confused with Ne-Yo (the singer) and Playstation "Neo" whenever I heard it in a podcast and the likes.
That aside, Nier has its core following and I'm sure that at least 95% of the first-week buyers played or at least knew about its prequel. I don't have think Nier has legs in terms of sales.
Nioh got much hype by just being similar to Dark Souls in game mechanics. I'm sure that 90% of the first week buyers also played and liked a Soulsborne game before. And its sales are already satisfying.







