in your personally opinion what anime, that had been change from its manga so much that they ended up having huge differences in stroy or ending, was the one that differ from its manga the most.
Hmm...Demon King Daimao (the anime) was much different in comparison to what Ichiban Ushiro no Daimao (the manga) turned out to be. The manga had much more character development and plot content that moved the story along for the characters while the anime headed off in a new, more "fan-service" based direction that made for some laughs but sort of put a damper on what could have been an awesome series had it been done right. Same thing with the Rosario + Vampire anime (which strayed from what the manga was doing and took things in a new, more ecchi-themed direction compared to what the manga had). How do I know? I own the manga boxset (Rosario + Vampire Vol. 1-10) and found myself enjoying the manga way more than I enjoyed both anime seasons. Heck, even Heaven's Lost Property (based off Sora no Otoshimono manga) modified things from the manga, but not to the extent that other series have done in the past.
Cardcaptor Sakura- Compared to the manga's 16 cards, the anime added in 36 more cards for Sakura to capture, featured Syaoran getting some cards (while he gets none in the manga) and a new supporting character, Meiling Li.
Full Moon o Sagashite- Compared to the manga's more somber and serious mood, the anime was mostly light-hearted in its exploration of Mitsuki's music career as Full Moon and gets increasingly more serious in later episodes. Whereas she was an immediate hit in the anime, Mitsuki had to struggle more at being a star in the manga. In addition, the manga provides more depth on characters who were otherwise underdeveloped in the anime like Meroko and Izumi. And speaking of Izumi, his character is much more likeable in the manga.
Kodocha- A lot of nutty comedy, filler episodes and breaking the fourth wall humor was incorporated into the anime, as the manga was a more traditional shoujo romantic dramedy in its focus on Sana and Hayama's relationship developments.
Love Hina- Will be a bit lengthy to cover here considering the different anime titles in the franchise.
Berserk- From what I recall between the TV anime and manga, the anime toned down on the graphic violence and sexual content of the manga, removed some major scenes in the manga (the Band of the Hawk's battle with Wyald, Guts meeting the Skull Knight for the first time, how Guts escaped from the Abyss) and retained a consistently serious mood throughout its run removing some moments of light-hearted humor with the characters.
Add in some more stuff:
Fruits Basket- The anime removes some scenes from the manga, adds in its own storylines at points (especially in the show's finale), moved around or changes some of the manga's storylines (Tohru meeting Ritsu and Hiro happens after the incident with Kyo's "true form") and removes mention of certain character traits or hints to events that occur later in the manga (the red cap boy from Tohru's past, Shigure's sinister side, Momiji being half-German, etc...).
Neon Genesis Evangelion- The manga reduces the number of Angels for the Eva pilots to fight, changes around traits and/ or backgrounds of the characters (Shinji being a bit more assertive yet angry from Gendo's neglect, Rei behaving more "human", Asuka being a test tube baby, etc...) and changes a number of events from the anime.
Manga also has a notable moment that makes me like the manga take of Shinji over his anime counterparts. Look below: