I've watched and read TONS of anime and manga throughout my life time and I'd love to share a few of my top choices with you all!~
((Also, the above illustration is not of an anime but of a Sanrio Danshi Boy, look it up (:))
Tokyo Ghoul and it's sequel Tokyo Ghoul Re are great manga. If you haven't already heard of it, Tokyo Ghoul follows its protagonist, Kaneki Ken, as what should have been the date leads him on a tight rope, struggling to balance himself between his human morals and his new lifestyle as a ghoul. Which also goes wrong. Everything goes wrong. Don't like someone. They're probably going to die. Anyways, unlike the anime, the many shows tons of elegant artwork and the characters are explored in so much more depth.
Nabari No Ou is another notable mention as it is a very underappreciated anime. This follows Miharu, a very manipulative, apathetic, boy who, despite his will, is smack in the middle of a modern day ninja war, hidden from the average human eye. The anime was much more appealing as the animation is truely beautiful and the soundtrack is very satisfying. I, personally, adore this title because of all the characters' backstories. They just break my heart and the ending just left me in tears!
If you haven't read, or even watched D. Gray-Man you are miss out, and I pity you. Following the protagonist, Allen Walker, the story sheds light on a war against Noah, a family of sins, and The Black order, a secretive organization that specializes in the distraction of Akuma. The artwork had so much thought put into it, and as the story unravels you definitely get mixed feelings about the order.
*Rolling in my sins*