If you liked the Mahou Shoujo Madoka Magica anime, the Anime-Planet community thinks you'd like:
In 2010, the Britannian Empire enslaved Japan using powerful mecha known as Knightmares; in the aftermath Japan was renamed Area 11, and its people began a hard and terrible existence. Lelouch, a Britannian student living in Area 11, has grown up hating the Empire and everything it stands for. One day, in the middle of a terrorist attack, Lelouch meets a mysterious girl who grants him the ability to control minds. Can he use his new power to fight for freedom, or will his hatred twist his good intentions into mindless acts of vengeance?
Both of these anime delve into the idea that often, great power comes at a price. With brilliant storytelling and plenty of psychological drama, these series are very much alike.
The main similarity between both Code Geass and Madoka Magica is that the plots invovle characters entering into contracts with mysterious contractors to obtain great characters. However, upon obtaining these powers the characters eventually fall prey to the powers that they have obtained. The situations of both Lelouch from Code Geass and Sayaka from Madoka Magica are comparable to one another since both characters enter contracts to obtain special powers, only for them to learn the truth behind their contracts, try to use powers that isolate them to help people, and eventually fall prey to their powers. While the plots are different, the reason why if you enjoyed one you'd like the other is that the two plots share similar themes, and are both serious takes on usually non-serious genres (the mecha in Code Geass and the magical girl in Madoka Magica).
The Holy Grail War is a battle between seven magicians who each summon a mythical hero to fight for their cause. Shirou, a twice orphaned high school boy, had so little magical talent that his foster father did not bother teaching him about the war and its meaning. Thanks to that lack of foresight, Shirou finds himself in a bit of a pinch when he accidentally summons a hero of the strongest class, and is sucked into the fray. The Grail grants the winner any wish they have. But driven by an unyielding sense of justice and self-sacrifice, for what will Shirou fight?
In both of these anime, characters either immediately get one wish before making a contract or fight for the chance at a wish after making a contract. Magical Girls/Masters fight other Magical Girls/Masters using magic, swords or various other weapons. As the stories unravel, they take form of a much darker element, producing two dramatic and similar fantasy series.
The archetypes of both Madoka and Fate are very much alike: both innocent Madoka and justice-desiring Sayaka are similar to FSN protagonist Shirou, while cynical Kyouko and repentant Homura are somewhat reminiscent of Archer. Themes of justice, hope, and wishes are strong in both series, and there are a variety of visual shout-outs in Madoka to FSN--primarily in the fan-nicknamed "Unlimited Musket Works" and "Unlimited Bazooka Works." It should be no surprise then, that the writer of Madoka, Gen Urobuchi, also penned the FSN prequel Fate/Zero; Urobuchi's end notes to one F/Z novel basically outlined his plans for Madoka.
Ultimately, if you liked one for its thematic devices, I don't know why you wouldn't like the other.
Ten years before Shirou Emiya's and Saber's fateful meeting, Japan is the stage for the fourth Holy Grail War. Seven Masters, each with his own dreams, step forward to win the boon of the mystic relic. Into this fray comes Kiritsugu Emiya, the enigmatic "Mage Killer" who wants to use the Grail to make a better world. Can he, paired with the indomitable Saber win the War? Or will he fall to the ambitions of the other mages?
Madoka Magica and Fate Zero have several key things in common: stunningly animated battles, duels that get your heart racing, generous helpings of magic and fantasy, and an interesting bunch of tragic characters that must rail against their fate. The two shows also possess similarly dark atmospheres, with their colours leaning towards crisp gloominess, and, of course, haunting music by Yuki Kajiura. Thrills and drama come naturally to these two shows, and any fan of one would adore the other.
Both are dark fantasy stories with magic, contracts, duels, death and lovecraftian monsters. All while being beautifully animated. (F/Z more so than Madoka.)
One thousand years from now, humanity live pastoral lives aided by psychokinetic powers and the subservient Monster Rats. Saki Watanabe has just come of age, and her power has been reined in through meditation and hypnosis. She joins the Unified Class, where she will learn about her power and the world around her; yet so much of the truth is kept hidden. Her friends Shun, Mamoru, Satoru, and Maria share in her curiosity, and decide to go out of their way to seek the truth. But will the secrets of the past and present turn out to be things that Saki really wants to know?
Both of these anime start out pretty innocent, with a bit of foreshadowing of darker things to come. And what do you know, the farther you get into the series, the darker it gets. To me, they definitely remind me of one another. I guess I might call them "sister" anime.
Both animes deal with preteens bestowed with powers beyond their capacity to comprehend. They also show the dire, hidden consequences that come with the price of being superhuman. In Madoka, the girls are influenced to choose to become magical girls, while in New World, the children are born with superpowers into a society that uses forms of brainwashing and thought control to keep the citizens docile. if you liked one, you'll surely like the orther.
Morimiya Yorito is a normal student who has an abnormal obsession for the sky. One day, he meets a strange girl named Shihou Matsuri who shares his interest, but as fate may have it, she isn't a human; Matsuri is a Yaka -- a "woe of the night" -- who is immortal and cannot stand the sunlight. A strange man is chasing Matsuri, to use her powers, so Yorito decides to help her hide. What are the strange man's plans, and what secrets does Yorito's sister hide?
Both shows start out as bright happy shows but slowly get darker as they go on. And both shows are about how it would really be if you were a magical girl and how it wouldn't be as fun as it seems. If you like one you should watch the other.
Both are dark, dramatic and full of feelings. In both the characters must sacrifice something.