Same goes for me, Ryuki was the first series that got me back into toku after running away from power rangers since it seemed childish at he time, and is still one of my fav series of all times.
Costume designs = superb ~ very unique to the point where all the riders have visor shaped faces, and only the main character and the alternatives retained their bug looks.
It was also ground breaking in so many ways since itw as the first series to introduce a riderfghting alongside a monster to defeat wild monsters, and the idea that Riders had to fight each other in order to survive. I remember most people who were hardcore Agito/Kuuga fans raged about that, but for me it was an interesting new idea and seemed really appealing. (it was so popular that even Fate Stay NIght took the idea and capitalized on it)
And it had cards...... I became a big nutjob in collecting cards because of what they dished out from Ryuki, and even till this day Im still hunting some of the cards I Missed back then. I also started playing MTG and YGO a year afterwards, suffering from how desperatly I wanted to play the RYuki card game but couldn't read any JPnese at the time.
Now as for the story endings, I like how they have multiple endings in each version of the stories, and the reset on the show was something that I couldn't get used to when I first saw it, even afer seeing it like 6-7 times. But now that some of you has brought to my attention about Shinji being the wild card, I'd have to say that it does open my mind up alot to the true intentions of what the creaters wanted for the ending. I guess if someone could find an article or report from when they interviewed the producers and writers at the end of the show, they might be able to find a blurb or something relating to what the guys up in the studio actually intended for the audience to see.
As for DCD, its a whole new seperate story, I won't even go there right now, but I still loved the show regardless. Same with Ryuki, the more times I watch it the more things come to mind, and the ending teaches us a great lesson in life. People in scifi shows who have super powers can reset timelines anyways they want, the rest of us however should make use of the time we have a do something profound with it, like Shinji who tried reaching out to different people.