^ Well said, SimbasGuard!
My personal opinion:
My vote on the poll went to Sarabi and Nala.
My top pick is Sarabi because she seems like (to me) the most wise parent. I feel like she and Mufasa are pretty much perfect characters, and as a mother I feel Sarabi has the same style/approach to parenting as her mate: She too can be both stern and playful depending on the situation. She`s clearly a loving mother, but she won`t accept any nonsense!
I think she, similarly to Mufasa, demands respect and is not afraid to put her cub (or anyone else) in their place with verbal correction.
I also voted for Nala. In SP, the focus is on Simbas relationship with his daughter, and so Nala gets pushed into the background, barely interacting with Kiara. When she does, she`s shown to be a very loving and trusting mother. I think Nala has still retained her fierce side from her youth, and would no doubt tell Kiara off like she did with Simba if she felt it was needed. Otherwise it seemed as if Nala was perfectly fine with leaving the lecturing to her mate (after they had rescued Kiara from the Outlands). She seemed satisfied that Kiara was safe and I didn`t get the impression Nala would adress it with her daughter, which is a little strange... In comparison, I imagine Sarabi had a word or two for cub Simba after he had lied to her about going to the waterhole! All in all, I think Nala is a relaxed mother with plenty of wisdom and life experience to pass on to her daughter.
Sarafina - She`s not exactly a very central character in the TLK universe, but I want to dedicate a part of my post to her in any case. I`ve read snippets of dialogue from an early draft of the film (the bathing scene) where Sarafina is telling Nala to stay clean for once, and be home before sunset! I think Sarafina is a gentle, protective and perhaps a bit fussy mother. Nala obviously turned out amazing, so she must have done her job right!
Kiara - We haven`t had a chance to see Kiara as a mother, but I think it`s fun to imagine her as a parent anyway... With her cubhood being so sheltered, I think Kiara would be more laid back than Simba was, and take a similar approach to parenting as her own mother, Nala, did. I think Kiara would trust her cubs and let them explore the Pridelands, though making sure they stayed within the borders. I imagine she`d be quite playful, definitly loving... I struggle to see her as a stern mother, I think it would be Kovu mostly handling the discipline. I picture Kiara being quite soft-hearted and would likely spoil her cubs.
Vitani - let`s just say she better do a better job than Zira did! And I`m sure she will. We don`t know much about Vitani, aside from her being loyal and strong... I find it hard to think about how she`d be as a mother. I do think she`d give her cubs more love than she recieved growing up, but she`d certainly not coddle them.
Zira - not much to say about her, she really wasn`t mother material.