i've watched enough to have a top 5 for Spring 2013 season anime
Hataraku Maou-sama! - easily my favorite show of the season. show has it all right IMO and the
#1 show i look forward to each week. main character is the devil from another world. gets his ass kicked by the hero of that world and runs through a portal to earth. comes out powerless and has to earn a living and gets a job at McDonalds and both hilarity and chaos ensue.
Suisei no Gargantia - the premise is starting to get tired because they're beating a dead horse but the art is stunning, the world is interesting and the characters are as well. this is the text book quality anime. does everything right to the letter and takes zero risk.
Kakumeiki Valvrave - this show is basically Code Geass 2.0. its a train wreck. its all over the place. its the type of show that's entertaining as hell despite its messy wild non-sense filled plot with excessive plot twist.
Yahari Ore no Seishun Rabukome wa Machigatteiru - the prototypical anime romantic comedy deconstructed. the male lead is an a$$hole with a heart of gold and the female lead is a total bytch and its fun to watch them go at each other. its elegant in the way it analyzes what other romcom animes focus on and rips their material and tropes to shreds.
Shingeki no Kyojin - this show is stunning when a titan attacks but when that isn't happening its average as hell. to me the main cast outside the female lead all suck and that really hurts it. that and the fact that 80% of the cast is underdeveloped and disposable.
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crap i watch but its not good.
Date A Live - this show is a turd. i don't even know why i watch it. its probably the car accident effect. can't help not to look as i drive past
Ore no Imouto ga Konna ni Kawaii Wake ga Nai. - this show is also a turd. in comparison to the last season the quality took a real nose dive and that's saying a lot because the last season wasn't the greatest. that being said i'm invested enough to finish it. most of the likable characters in the main cast (what few there are) like Kuroneko have had their screen time drastically reduced.