So hard to choose... "One by One" is definitely up there though, in part because in the genius of this franchise the lyrics have next to nothing to do with the story itself if you know the Zulu translation (
http://www.lionking.org/lyrics/OBCR/OneByOne.html) -- I listen to a lot of South African music and spent a couple summers there, so I've managed to pick up a little Zulu -- which is literally a black pride song that roughly translates to something like "This brown color is my shining armor and I'm proud of it".
(In fact, it's been covered by various artists from the country, including Hugh Masekela (
https://www.youtube.com/watch?v=m4F6hH_2y7I), whose "Grazing in the Grass" was actually covered by Raven-Symone for
The Lion King 1 1/2:
https://www.youtube.com/watch?v=gUflTWPL7Cs. I'm going on a long tangent here, but I really hope that Masekela gets involved in the music for the remake; I'd die...)
Keeping in mind that Lebo M. and the rest of the S. Africans involved were effectively exiles from their home country when
The Lion King was in production, it makes their musical numbers that much more poignant because most of the Zulu, Xhosa, and other S. African lyrics in the franchise connect the lions' story to that of South Africa at the time, with Scar and the hyenas being a stand-in for the Apartheid government, and Simba and Nala were effectively the exiles forced to escape and find help to overthrow the oppressors who'd taken over their homelands. I just think that's part of what makes
The Lion King so powerful (both the film an the stage version); it was, in a way, a vehicle for political protest in a real-life fight for liberation, whether Disney and its Western audiences actually knew/know it or not.