[{quoted}](name=Espy Psyche,realm=NA,application-id=3ErqAdtq,discussion-id=k9fxPE0A,comment-id=0003,timestamp=2017-10-16T10:13:23.804+0000)
This is a symptom of a larger problem -- Nashor's Tooth and some other items are exceptionally weak, and the value of stats as a whole in the game are way off.
This is the same reason Orianna and Diana don't build Nashor's despite having synergy built into their kits, why Vayne built crit for the longest time instead of going on-hit, and why Lucian/Corki don't build Manamune.
There's several items in the game that need buffed, Nashor's and Manamune among them, but that won't solve the issue. The only thing that would fix this whole thing of "OP items" being better than "synergy items" is for the stats of Attack Damage and Ability Power as a whole to be reworked. There's only a couple of champions in the game that can justify building an Attack Speed item first, and that's because Attack Speed as a stat is too weak.
Teemo and Kayle can use Nashor's Tooth effectively because they benefit a lot from the attack speed.
Diana is melee so she needs to build tank if she wants to autoattack reliably in teamfights. You can just build her burst and not worry about that. Nashor's doesn't work in a tank build, as it requires AP. Diana could get away with a Wit's End in theory, but her burst build is so strong why even bother with some tank bullshit?
Orianna can sorta get away with throwing some autoattacks but her passive is not strong enough to justify an autoattack focused build so she isn't enough of a threat with that build, especially compared to the burst she's capable of if she builds full AP.
Vayne gets a huge AD boost in her ult so she's better off scaling that AD with crit. Her W is NOT her strongest feature. That's just a stupid meme perpetrated by silver/bronze players.
Building onhit isn't about the items being strong enough compared to crit or AP or whatever. It's about having a champion kit with enough synergy with those items.