Looking back, would have loved more Aja and less Kimber
My favourite character in Jem is, and always has been, Jem herself. By far. No comparison.
Second would be Jerrica, her alter ego.
But among the rest of the cast, my third-favourite would definitely be Aja. What a pity that of all of the Holograms, she had the least screen time, and never really got an episode of her own.
I LOVE the fact that, at the very least, she was involved in one bona fide romance -- with Stormer's brother. (That's actually rather funny, in a way, because all three have blue hair. I suppose this was a Jem in-joke, that all the blue-haired characters would be related to each other or attracted to each other.)
By contrast, the series gives Kimber way, WAY too much screen time. She's a whiny, self-centred brat. I do like her more than Shana and Raya (because Raya proved ultimately to be completely useless), but still, I would have loved to have seen more of Aja. She was the second-prettiest Hologram, after Jem/Jerrica herself, and also the second-most interesting.