Attack on Titan doesn't have a ray of sunshine within it. The series kills off any goodwill and optimism quickly. Demon Slayer, on the other hand, uses dark themes to show that the world isn't as cruel as it sometimes seems. Even though demons eat human flesh, Tanjiro tries to see them as people with feelings and dreams.
Death Note features an intelligent cast and a plot full of gambits and twists. The series may take itself too seriously at times, but it's still a welcome addition to any anime fan's shelf as well as a great gateway into anime.
Code Geass is full of twists and cool mech battles. Attack on Titan doesn't know when to have fun, while Geass has its share of wacky filler episodes. Lelouch's planning ability heavily outweighs Eren's. The two shows are hard to compare in some spots, but Geass ultimately wins out.
Fullmetal Alchemist never shies away from killing people off or having tragedy happen to prove a point. Attack on Titan does this, too, but in a much more mean-spirited way. Eren and Edward are both the products of science, but there seems to be a point to alchemy, while Titans are only meant to destroy.
Attack on Titan has its share of fans, too, but it is totally opposite tonally. The series doesn't bother with an adventure theme. It's all about crushing dreams instead of fulfilling them. Because of this, it doesn't have the overall appeal that One Piece has.
Black Lagoon revels in its sometimes ridiculous cast of characters and epic battles. Attack on Titan, on the other hand, takes itself way too seriously and doesn't execute some of its story elements correctly. Eren is fueled solely by hatred, while characters like Revy and Dutch are after something much more. Granted, Revy is mostly after money, but the reason she gives for loving guns and money is understandable.
Jujutsu Kaisen proves that one can tell a story about horrific things and not take itself too seriously. Attack on Titan has the issue of just piling on more and more terror without giving audiences a chance to breathe.
One of Kino's most famous lines is, "The world is not beautiful, therefore it is." Attack on Titan could learn a thing or two from that mantra. The series stacks terror after terror with little chance for recovery, especially in its closing chapters.
Attack on Titan takes itself a little too seriously and mistakes gore for maturity. Cowboy Bebop is like a finely roasted coffee: bitter but refined and goes great with jazz and rainy days. It's sophisticated fare that is refreshing and wonderfully executed.
Attack on Titan uses its views on morality as a soapbox to coerce its audience into thinking that intolerable acts are justified. Monster uses Dr. Tenma as a moral compass to show that people deserve compassion and understanding. Monster's flawed characters only enhance this message. The series is truly wonderful, with masterful writing and suspense.