Alright it's been quite awhile since I have played Legends of the Arena, Vega or Dark Rising as I have beaten them awhile ago but I just beat (or rather caught up to) Pokemon Desolation and you definitely won't be disappointed with that one. I can't really explain how "good" it measures up to reborn because I beat that awhile back also but I think it's better than Rejuvenation for sure. The depth of the characters are pretty good and the world building / story is also good in my opinion. You'll just have to give it a chance.
Now for Legends of the Arena, the story is lighter than Reborn so it won't be as good if you're looking for something very similar to Reborn but if you're just looking for a good story & game play at the same time, LOTA is amazing at that & it's a very unique game.
Pokemon Vega well like I said before it achieves difficulty without the need for bullshit and it's stories pretty good. All that can be said really, been too long.
Dark Rising series, well just search it up on google to be honest, it's an extremely popular fan-game and is dubbed as one of the hardest. It actually does have a lot of story though, especially I think in the 2nd version but it's been a very long time so welp.
All in all, just try them lol, no point in me trying to convince you what you'll like, we aren't friends. I don't know what'll make you excited or annoyed. You can search them all up, read descriptions and form your opinion on whether you would like to play any of them.
(Typing at 3 am so idk how to explain this better really.)