I prefer Rejuvenation over Reborn. I find replaying Rejuvenation is much less tedious and more enjoyable than Reborn. Some of the routes of Reborn are just too long and so tiring to get through (e.g. that route in Reborn with the rocks and the Crustle is SUCH A PAIN). Also, I prefer Rejuvenation's story and overall aesthetic a quite a bit more over Reborn's. It think it's because I feel like there are occasions where Reborn is trying too hard to be edgy and dark. It's always grim. Both definitely have their flaws though. The two games suffer from having characters that are randomly just thrown into the plot. Rejuvenation suffers more from this I think, especially after V9. Reborn suffers from this problem to some extent, but I think my main problem with Reborn is that it doesn't do a good job at developing some of the characters which makes them forgettable. For example, how much do we really know about characters like Noel and Anna?
Ultimately, I agree with the sentiments of another comment here where they said that it is difficult to compare the 2 games fully as both are not finished yet. But right now, Rejuvenation is winning it for me.