[hider=anime] 
I'll leave out some details don't want to spoil it after all.

Toradora

I don't even know where to start with this anime, it's based off the light novel by Yuyuko Takemiya who also made Golden Time and had a manga made of it (which is also recommended). I've watched slice of life's before but when I came across this one it hit me and I couldn't stop watching it. The story is about a boy name Ryuji Taksasu and a girl named Taiga Aisaka who band together to help each other with their respective love interests which happen to be the two's friends. Watching the two of them try to gain the affection of the people they love was endearing but even more was watching the two of them grow and support each other through the series. The trials the two had the face, selfishness, hate, betrayal aaaah it's so good I'd watch it over and over again. (Which I have but you get the point). It has a nice dose of humor, the voice acting is great (japanese anyway, english dub is meh). The OST is memorable and when things get serious it's hard for the heart not to pound. I'd recommend this to my worst enemy.
[youtube]jBup5tTEWAA[/youtube]

Clannad

The feels....that's...that's all this anime is, it's made by KEY who just...just...hurt...KEY hurts. Anyway the anime revolves more around the characters and how their world is shaped and changed by one another. It was a VN before so there are 'routes' in a way and each one is equally painful to watch but it's so engrossing it's hard to look away, there aren't always happy endings so be prepared for that. The anime mixes a good blend of comedy and tragedy which I don't get to see very often, it's hard not to fall in love with the characters as well. 
[youtube]P-zhIImKP5k[/youtube]

Hellsing(OVA)
With respect to those who have read Twilight and Vampire Knight (I've read them as well to be fair) I will withhold my comments on a proper vampire and skip right to the core, this anime is beautifully done. The OVA's follow the manga so I'd recommend them over the tv series (though it's not too bad it doesn't have the depth the OVA's do). The stories revolves around the Hellsing Organization who hunt those that bump in the night, they are situated in London and to put it simply they get stuff done. I can't find the words to explain this anime and the things it touches but just...blood, gore, insanity, religious affiliation, vampires, guns, and explosions. If it hasn't been seen I'd recommend it.
I'd say watch it in English cause of the accents and the voicework which is really good, nothing like a Scottish bayonet wielding killer's monologue but I'd say listen to it in Japanese once...just to hear Alucard voice Jouji Nakata....just...all day. The animation not bad either.
[youtube]RF-5VWT62HY[/youtube]

Samurai Champloo
Samurai wielding swords and fighting during the edo period with hip hop influences nuff said. Kidding aside the anime is roughly about that, a break dancing foul mouthed samurai and a quiet samurai with insane kind of speed accompany a young girl looking for another. Watching the three interact with each other is funny enough but add in fight scenes, some character development, and a soundtrack that compliments all of that perfectly and you have a good gem worth watching.
[youtube]4OuRajFzMYI[/youtube]

Watamote
I went into this anime with low expectations actually but I figured eh why not, couldn't hurt to watch a few episodes. Eight episodes later day was breaking and I was staring nine. The anime follows a female protagonist who is...to put it simply an otaku entering high school with the expectancy of being popular, this may have been seen before, minus the otaku part or a few other tidbits but the way this anime handles this girls journey is beautifully done. The animation isn't flashy but it compliments the casual style, the facial expressions sell her emotions almost as much as her inner monologues and watching Tomoko blame the world for her unpopularity is unnerving but endearing at the same time, even more so when she comes to realize she may have a hand in her solitude. I see plenty of anime with a beautiful well groomed and well mannered protagonist beloved by all or many, not this anime. She barely exists and tries immensely hard to fix that, some things in the anime may even touch home for a few people.
[youtube]HAIAXFQ0T74[/youtube]

If it wasn't clear from the selection I love me some anime with feels and character development, Hellsing is the only one of those with more story focus. 
I sat for hours trying to narrow down anime and I figured I'd be there all day so I avoided any from the recent seasons and just stuck with some older ones that made an impression. (Except Watamote which was in 2013 making it more recent)
There are some honorable mentions like Ghost in the Shell but I'll be here all day if I don't stop here.
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Of course One piece would be on there but I can't deny I agree with you, I did watch soul eater and Deadman Wonderland though I haven't finished the former, first episode of Deadman Wonderland drew me in. I haven't touched Durarara and Gurren Lagann...but my friend loves Gurren Lagann, and keeps offering to lend me the DVD, might take him up on that now.