Picking between S and stars is nearly impossible for me but I went with stars just bc I rewatched stars for the first time in ages and fell inlove all over again. Love the starlights the lack of fillers and a much needed break from chibi usa
S without a doubt.I loved everything: the dark storyline, the villains (proffesor Tomoe and Witches5 are my favourite ), the messiah stuff, Haruka Michiru and Hotaru, the epic final battle, the beautiful soundtrack...
The Nehelenia's return arc in Stars comes second. It's almost as dark than S and watching the Inners and Outers fighting togheter was awesome. I'm always think that this arc is somehow the Stars "movie". lol
I've only watched Classic, R, and the first 7 or 8 episodes of S. So far, my favorite is Classic, though I do think the final 10 or so episodes of R are right up there. It's too early for me to properly evaluate S, though I'm hoping all the praise it gets doesn't over-hype it for me.