Private 'lessons' with sensei, in glorious 3d pov.

What is a good anime like One Piece and Naruto that I could watch for a long time?

Hunter X Hunter Synopsis-A Hunter is one who travels the world doing all sorts of dangerous tasks.
From capturing criminals to searching deep within uncharted lands for any lost treasures.
Gon is a young boy whose father disappeared long ago, being a Hunter.
He believes if he could also follow his father's path, he could one day reunite with him. After becoming 12, Gon leaves his home and takes on the task of entering the Hunter exam, notorious for its low success rate and high probability of death to become an official Hunter.
He befriends the revenge-driven Kurapika, the doctor-to-be Leorio and the rebellious ex-assassin Killua in the exam, with their friendship prevailing throughout the many trials and threats they come upon taking on the dangerous career of a Hunter. Hunter X Hunter is written by Togashi Yoshihiro who is also the writer of Yu Yu Hakusho.
Mashisho Kishimoto openly admitted that his series Naruto has been heavily inspired by Hunter X Hunter, and it is also common knowledge that Tite Kubo's Bleach was also heavily inspired by Togashi's Yu Yu Hakusho. HxH is a must watch series which contains from an adventurous examination (Hunter Exam) to a dark neo-noir thriller (Yorknew), the series features 5 main story arcs that vary in nature and tone.
HxH arcs are also connected with one another, with each arc naturally following the one before it.
This creates a realistic transition that is uncommon to the genre and highlights what the series really is, a journey.
Pacing and development are also excellent.
Episodes for the most part are enjoyable; rarely do you feel that an episode is "dragging" and when you do, you are left with a feeling of story progression. However, what sets the series apart from other battle anime is its unorthodoxy and unpredictability.
Shonen tropes and storytelling methods are undermined throughout the series.
The main character for example, Gon, fails more than he succeeds.
Power-ups based on emotion or willpower are non-existent and fighting in the series is radically different from other battle anime.
The main protagonist is not the main focus of every arc either. Presently, it has over 130 episodes and the manga has reached about 350 chapters.