Yes, I agree, it would be nice to compare all of the Annie's voices. There were some videos of Albert's Angels doing Een Zwaar Bestaan, but they appear to have been removed. What a shame. These are the Annies whose voices you can compare:
4. Sharon Witsiers sings many songs on the cast album- Hard Knock Life, Think I'm Gonna Like It Here, Won't Be An orphan For Long. Email me and I can send you the full CD (zip file). Not sure of Julie's downloads policy...
She also features a little in a YouTube video (read on)
6. Marieke Swart and Esmee De Boer alternated as part of the same orphan group, De PodiumRakkers, after the show moved to the Efteling and they did an interview together. Marieke, in costume, sings a bit of Morgen at the end. http://www.youtube.com/watch?v=R1j5lm4Bk7Y
The footage shown from the auditions about halfway through, features Sharon Wisiers singing a piece of Morgen, too.
Kika did an appearance as Annie, which she admits in the comments was not her best performance of Morgen. In a comment in Dutch, she apologises and says that she was too out of breath from doing Een Zwaar Bestann (the full stage version, not edited) to sing properly and of her three takes, they used the worst one.
Many Annies and orphans had also appeared in the Dutch version of The Sound of Music 2001/2, a few years before. As for Annie, 10 groups of children were cast and there's lots of videos on YouTube.
Kika was a Gretel and both Stephanies were Martas. Lizette Hart, who played July alongside Neeltje De Vree in De Weesgrietjes, was a Brigitta.
The one video I can recommend is this one. A very young-looking Stephanie Van Rooijen is playing Marta and Lizette is playing Brigitta. Kika and Stephanie Vertraten were in another group, but they are both in a picture on Stephanie's website.