I've already watched Sakamichi, so if I had to choose between the two I'd probably go for Mirai Nikki instead.
I guess I'll also suggest Kyousougiga while I'm at it, since I kind of liked the surreal setting I saw in the first episode. While I've already watched it, I kind of liked Maiden of Dusk (Tasogare Otome Amnesia, I think), so I'd recommend that as well. The only caveat is that it isn't available in LatAm, so I don't know if that means the show suffered the same fate in Europe.
Another would 've been decent-ish for a Halloween watch, but I can't say it was all that great. The first part was creepy in a moody, somewhat David Lynch-esque way (actually not even close, but still)... but then it became little more than a Final Destination ripoff, which disappointed me greatly.