Cross Channel is very interesting, it slowly builds up and gets more and more interesting and then it ends. The ending I wasn't a big fan of, but it's definitely worth going through.
Yume Miru Kusuri is not bad either but it gets a bit ridiculous at some points, not a fan of the ending of Aekas ending.
And then lastly Da Capo II is in my opinion a lot better than Da Capo, the sisters also have my favorite routes (well at least Otome, never really been a fan of younger sisters) and I would say Kokos route is probably the shittiest. The rest I haven't bothered to play yet, which means I have found something about them more or less off-putting,