[MiS]

Do you use MyAnimeList? If you don't, it's quite an easier way to keep track of what you've seen and what you'd like to see.

I'm really glad you've watched Index, Log Horizon, Durarara and Steins;Gate, I personally finished those quite recently and would rate them pretty high.

If you like gore, I'd really suggest Another, which is a mixture of mystery and horror. I'd also suggest Elfen Lied like @Jiggly said, which I'd go so far as to say it's a classic. If you like shonen and fantasy, I'd probably recommend to you Shakugan no Shana. Magic, you should try checking out Magi.

Personal recommendations would be Toradora! and Chuunibyou, which are both romantic comedies.