Nidalee double morello

Facing the option of a second Morello's or a Morello + Athene's... I'd take the second Morello. It gives a little less mana regen, but it does give 20 more AP, and, oh, costs 600 less gold. Part of the reason for double Morello is the almost absurd gold efficiency that, frankly, Athene's doesn't match. And it doesn't help that it doesn't come close to matching it, while costing more 600 more, for less AP and some MR instead, which you may not even be in dire need of.

I'm too lazy to do the math, but Athene only has 50% bonus and scales with max mana so maybe because she doesn't realy buy any mana items this is more efficient. Or maybe It's so unnoticeable either way they can just do whatever they want. Or maybe like you said they are just sheep and pick the worse choice.

Athene's regen is pretty shitty now bro. Nid has almost 20 base mana regen at lv18. In order for athene's to break even, it needs to restore 10 mp5 from mana font. At 1000 base mana at lv18, if she isn't also building mana items, she'll be getting... about that much when she's at 50% mana. Now, morello is giving comparable regen, comparable CDR, more AP, and comes at a lower cost. Unless you're in dire need of that +15% missing mana on kill or assist, stacking morello is simply better. This logic applies to all AP champs that want 40% CDR and some mana regen. If double morello isn't solving your mana problems, only then would you consider building athene's.

You can call people sheep all you like, but it doesn't matter as long as they're sheeping something effective.