I actually liked all of the characters in steins gate, although I suppose watching it after Tokyo Ghoul might have made the characters seem so much better.
But yeah, Steins Gate definitely one of the best.
And yeah, honestly reading the synopsis of Parasyte a little while ago, it didn't really stand out as anything spectacular, but watching it, I think the plot is executed well and definitely worth watching :3 I'll probably be finished it by tonight...
Okay I know this is probably sarcastic but is anyone else reminded of the people who join and stay in games while also continuously complaining about how bad the setup is and not contributing to the discussion? Lol.
Mirai Nikki sucks because the main characters suck and the story starts being really stupid, too.
I haven't seen a lot of the recs here but Steins;Gate is the bestestestestest. :D (If we're on the topic of sucky characters, though, its entire side cast is ATROCIOUS.)
Puella Magi Madoka Magica is pretty well-liked. It's a deconstruction of the magical girl genre and, despite its flaws and semi-banal premise/aesthetic, I found it pretty good overall. I had trouble making myself watch it at first because of the cutesy art so I had to mildly spoil myself before I started it. xD Get to episode 3, maybe.
I mainly recommend that one because it fits into your twelve-episode ideal, though. Not especially sure you'd like it. Let's see... uh... what else is twelve episodes? Lol.
A lot of twelve-episode shows are very poorly paced. I think Paranoia Agent might be that long? Idk, I'd have to check.