Even a little or just a lot? I'm interested. I cried multiple times during "IS - Otoko demo Onna demo Nai Sei"... it's different from usual manga and it really opened my eyes. (Read it while I was going under similar circumstances as a few of the characters.) I also think Naruto has taught me a few important things growing up... it'll always be in my heart. Excuse my corniness please. I'm a very sentimental person.

So, name a manga please, if you'd like.

The cornered mouse dreams of cheese
And its sequel Sojou no Koi wa Nido Haneru

Sakura Gari

Those three are A MUST READ.They aren't just my yaoi favorites they go beyond those "barriers" I consider them masterpieces.

I also have some others I won't say "changed me" but that I still consider extremely good and emotionally strong:

Doushitemo Furetakunai.Don't forget to read the doujin !
Aiteru Door kara Shitsurei Shimasu yo
Saigo no door wo shimero ! and its sequel
Doushite Namida ga Derunokana
(Yeah I'm a fan of Yamada Yugi as you can guess .I could go on an on with recommandations of her work so I only named my favorites but I suggest you check her other stories too)
Mirai no kioku + sequel
Endless world

As for Yuri...I love it but never found one that stroke me and somehow taught me things so I can't recommand you any.

Yes, I have.
It is called Complex and it was one of the most touching stories I have ever read. I tell the story of two lovers, from the age of 11-12 and until (really) old age. It's one of the , most beautiful stories out there- i have no words to describe it. Just read it, it is worth !

Little Butterfly
Zankoku na Kami ga Shihaisuru
Sakura-Gari
Seven Days
Complex
Doushitemo Furetakunai
Koujitsusei no Tobira
Yatteraneeze!
Sakende Yaruze!
Kanpeki na Koibito-This main story is terrible but I love the oneshot on chapter 5.

________________
"For in all the world there are no people so piteous and forlorn as those who are forced to eat the bitter bread of dependency in their old age, and find how steep are the stairs of another man's house. Wherever they go they know themselves unwelcome. Wherever they are, they feel themselves a burden. There is no humiliation of the spirit they are not forced to endure. Their hearts are scarred all over with the stabs from cruel and callous speeches."

Definitely Sakura Gari. I don't think it can leave anyone indifferent..
Coponicus no Kokyuu is really dark and disturbing.
Banana Fish is a masterpiece. although it's not really yaoi.