One Piece, Nanatsu no Taizai Recommendations
Both anime focuses on searching for friends/teammates ("nakama") while going on variety of adventures and each character has a unique personality as well as abilities that makes them strong and reputable, meeting different people and constantly being chased by the law enforcements in the story. Ultimately, the protagonist and his friends hope to obtain their goal.
Both series have:
* Protagonists are introduced in a bar where a once merry/drinking mood is interrupted by baddie
* solid world building that creates a distinct world
* misadventures and exploration
* Unique art style combination with a touch of Dragon Ball
* Similar slapstick humor (how do you poop vs. groping/panties
* historic setting (pirates & knights) with a new spin on classic stereotypes
* a bright color pallet of settings
* a rag tag band of loveable misfits
* Light Hearted at first glance with a more darker and mature back-drop in the back
* Similar feel
* Battle Shonen
Like One Piece, Nanatsu no Taizai(Seven Deadly Sins) has a general feeling of a very enjoyable happy-go-lucky mood punctuated with serious intensity fights while going on a exploration style adventure. Both of the anime's main protagonists are a group of misfits picking up members one by one, each of which all have special backgrounds making each of them overpowered compared to most fighters in their series though they still have to make an effort in fights. Due to being overpowered, neither series sees a lot of "level-up" events for their characters. And though each series protagonists like to act tough, they are very moral
Both are adventure manga with a lot of battles. The protagonists are both rather careless but would do everything for their friends and there are also a lot of different characters with very unique abilities and character traits.