I have read the manga, watched the anime, watched all the musicals, watched the live action TV show, as well as the live action TV stage show and watched Crystal so... I will say this, I loved them all except the live action Tv show. It was fun to watch up to the end where... lets say, a critical character went WAY not canon (no spoilers).

But to your point, Crystal is more fast paced but that was not necessarily a good thing, the first season was panned by some as not personalizing the characters enough, that is, if you already knew and loved the characters then you could kind of flesh them out with your memories, but If you had not already seen or read Sailor Moon you might find it a bit dry and maybe be left wondering what all the fuss was about. I'm saying it might not hold her attention, depending on how much of the original anime you watched.

So I'm leaning towards the original anime which had much more time to flesh out the characters, if... you did not finish at least the first two seasons with her, if you did, she should have a great grasp of the characters and that should carry her through Crystal.

Everlasting moonlight!