10 champions objectively better than Nid in URF: Hecarim, Sona, Soraka, Malzahar, Lulu, Zyra, Kayle, Lux, Jayce, Urgot.
Malazahar is short ranged and most of his damage is DoT. He isn't mobile. He'll be better after the crab AI patch, but he's certainly not better than Nidalee. Sure AD Malz splitpushes like a boss with with the cooldown on teleport and his lack of mobility he'll be suicideing to do so most of the time.
Lulu is basically a shorter range much lower damage Nidalee with more C.C in this mode, but she'll get blown up in most cases before she can spam Poly. Also Glitterlance is a lot less impactful when everyone has dashes every 2 seconds.
Kayle's ranges are too short and even with Intervention's cooldown it's not that good. Especially as any C.C at all messes her up, and again, short range.
Lux is worse than Nidalee. Nidalee is hard to catch and kill. Lux is not.
Jayce is basically a less mobile AD Nidalee without a massive heal.
Nidalee is complete hell to play against at every phase of the game and is really, really hard to take down outside of targeted, homing C.C like Twisted Advance. You cannot underestimate her Primal Surge either, she wins battles of attrition with ANYONE. [Except Sona]
Zyra's too hard to compare so I went benefit of the doubt there, and the others probobly are better [Urgot Charge = Dead, Blenderrim and walking fountains]
Now excuse me while I spam
Super Galaxy Rumble.