Takarajima

Ie Naki Ko and Takarajima are both adaptations of Western novels in which a young boy leaves home and travels the world accompanied by a charismatic father figure and animal companions. They were made by a lot of the same people - e.g. director Dezaki Osamu, character designer Sugio Akino, and art director/background artist Kobayashi Shichiro - and released one year apart. The visual similarities are extensive and obvious. As for differences, Takarajima is a pure adventure story, whereas Ie Naki Ko puts the emphasis on Dickensian drama. 

Mysteries and crimes of the past become the source of greed, conflict and murder in the present. All characters have their agenda and more or less sinister goals (with exception of Jim Hawkins and Miyuki Tanokura maybe). It is the most capable guy in both series who gets things rolling... If you want to see various factions fighting over something robbed that was hidden long ago, these titles may be for you.  

Both anime are about pirates with great adventures, fights, awesome characters and most importantly, the direction of One Piece is often inspired by the direction of Dezaki Osamu. 

May seem like a weird pair of anime to compare to each other, but there's more in common here than you might expect, besides the obvious "Oh hey, Dezaki is at it again with his god-tier anime" While slightly more lighthearted than Ashita no Joe, Takarajima has that same indescribable vibe that AnJ pulled off so well, quaint living, same ability to swing from dramatic and tense to slow and cozy. Both are pretty damn good for 70's anime, and both are able to pull in an audience that otherwise wouldn't bat an eye at sports and piratey anime. The series are both focused more on the characters than the actual "objective" of each anime. Characters feel realistic and consistent, Jim being a 13 year old, acts irrationally and without sense of self preservation, and Joe being a street urchin living with nothing his whole life, is a delinquent who has a really messed up moral compass, both improve and develop rapidly throughout the series. Ashita no Joe tries to feel as realistic and visceral as possible, whereas Takarajima is okay with bending reality a tiny bit, though neither of them hesitate to put you through some emotional hardship, with how they make you love the characters, then put them through absolute hell. I've cried watching both, which ain't easy to do to me, so I feel that's also worth mentioning. Without delving into sequels (Or speaking in enough detail to spoil anything), I liked the endings for both, it made me feel like I had watched a once in a lifetime type of anime. Both are absolute masterpieces, and with both of them having really good quality fansubs (And proper HD remasters), you shouldn't sleep on either of them. read more 

Adventure time!! Leaving home to go on a grand adventure, seeing places they've never imagined, and thwarting the bad guys. Old school shows that dont lack quality. 

Although the settings are different, both are enjoyable historical adventure anime focusing on characters who are searching for a hidden treasure. Both contain lots of action, twists, and funny moments. 

The child protagonists in these series are about the same age when they embark on a ship to find a long lost treasure. They both form a close relationship with an experienced sailor. If you enjoyed the mentor-protégé connection between Esteban and Mendoza in Taiyou no Ko Esteban, then you will most likely feel the same about Jim and Silver's in Takarajima, and vice versa. Both Mendoza and Silver are charismatic yet cunning leaders and father figures to the young protagonists while pursuing their own agenda. They will do anything it takes to find the gold. Both series are old-school children's anime that have adult characters in prominent roles. read more 

Both series follow a young boy (Jim Hawkins in Takarajima and Yuu Tagami in Giant Gorg) as they explore an island looking for unknown treasures. Giant Gorg's Captain is also fairly similar to Long John Silver, especially considering his moral ambiguity. Giant Gorg likely had some inspiration from Robert Louis Stevenson's classic tale. Their similarities are just too great. 

While both series have very different stories they do share the concept of meeting a charismatic man whose allegiance is shrouded in mystery; The Count Of Monte Cristo and John Silvers. Other common traits are parts of the story being centered on betrayal and murder.  

Same director telling a story about a crew of pirates led by their manly captain while bearing a thrill of adventure. 

Both shows share a lot of the same staff, director Dezaki, character designer, composer, and maybe even more. Beyond that it's easy to say these are some of Dezaki's simpler shows with more straightforward storytelling and a great emphasis on adventure and action. Although wildly different settings, you could almost picture Silver in Cobra's world or Cobra himself as a pirate ... since he is one of the future! So yeah straight up if you like one of these you'll probably enjoy the other.