Bro you're BUGGING.
I just re-watched a bunch of Greed Island this weekend because I was tired of lackluster, one-dimensional anime and threw HxH on at a random episode. Arc is hype for multiple reasons:
1) When contemplating that this entire game world can be built with nen within the confines of how it is explained within the show, that's just mindblowing
2) The Binolt training portion is hype
3) Killua goes back to take the Hunter Exam and takes out every other person in order to pass - which shows the amount of growth he's achieved since learning nen since there's no way he could have done that non-lethally before
4) We are exposed to even more non-lethal / non-battle nen abilities via the nen exorcist, which further deepens the world
5) Gon actually develops his hatsu into Jajanken, and FAILS to figure out Paper (a shounen protagonist NOT perfecting his technique before the big conflict? how often does this happen?)
6) Genthru blows up all the weaklings
7) Hisoka interacts with the Troupe, setting the stage for the most hype battle in the series (manga only for now)
Dodgeball game further shows Gon's digusting potential
9) Fight against the Bombers - first battle usage of Killua's hatsu, Bisky going ape(literally)****, and Gon SACRIFICING AN ARM JUST TO BE RIGHT, THEN K-Oing GENTHRU
10) A catch all for all the little strategic moments that I feel really make the show special: Tsezgerra's strategy to run from Team Genthru and Genthru's rebuttal by checking all people who leave the magic shop, Genthru's immediate recognition that Gon knows his abilities and his tactical shift from there, Killua's plan to find bums holding onto their cards and trading with them for Leave cards, Hisoka figuring out how to explain his presence as Chrollo without revealing the nen exorcist and Killua finding out because he realizes Hisoka is bored, etc.)
11) Gon beats a game that stumped top-tier hunters for YEARS, and also happens to literally be made for him to grow stronger, which we find out as we learn more about Ging in this arc than we probably do in any other arc. And the arc is also only 15 episodes - not very long, and 5 episodes less than Yorknew
I'm not going to sit here and say Greed Island is the best arc (it's definitely top three though). I'm just saying that there's really a ton to unpack within that arc and Togashi is able to maintain / balance consistency in a masterful way. It's super interesting because it's primarily a training arc that really helps Killua and Gon come into their own with their nen abilities. It also doesn't try to manufacture super high stakes - yes, Genthru is a bad dude, but Gon is mostly playing this game because it'll help bring him closer to his dad, which is his ultimate goal (not becoming the Hokage, Wizard King, the Greatest Hero, or whatever else). Outside of the Bomber fight and Dodgeball there's relatively no action, but if you can appreciate the growth of Killua and Gon and the strategic approach they take to winning the game then it's pretty rewarding.
Also, if you classify Gon as just an always happy dude then you're missing a large chunk of what makes the show special. Gon is an inherently selfish character with a strong positive outlook (mostly because his enormous potential allows things to go his way most of the time), which really boils down to him being immature. His immaturity (and selfishness) is his most distinguishing factor compared to most shounen protagonists (I'd say Luffy is closest), and we see it factor into key moments in interesting ways. In Greed Island alone, we see two major instances: 1) when he (knowingly) DESTROYS Killua's hands while using jajanken to shoot the ball at Razor and 2) when he puts all of the work that Bisky and Killua did at risk during their battle with the bombers by sacrificing his arm, just so he can try to beat Genthru on fair footing - there was literally no reason to do, he just wanted to try it. The most impactful instance of his selfishness is the way he treats Killua throughout the Ant arc as he grieves for Kite - it's clear that he's immature and still just a child. His immaturity is what ultimately allows him to defeat Pitou, in that he's not thinking about what's "right" or "good" anymore - his aura during his interactions with Pitou is not pure, it's corrupted and tainted with hatred. His immaturity allows him to cast away his life's potential in order to beat a singular entity - his desire for revenge meant he couldn't wait to reach a point where he could beat Pitou through training, and so he cashed out his life's potential to destroy him, fueled by hatred. And it was REAL. This wasn't Ichigo randomly getting a new mask and destroying Ulquiorra, it wasn't Naruto going eight tails against Pain and then finding himself again - not only did Gon legitimately almost die and need to have an arc dedicated to his healing, BUT HE LEGIT CAN NO LONGER USE NEN ANYMORE. DONE. OUT OF THE STORY.
The true beauty of Hunter x Hunter is in the details, the consistency, and the depth of the characters. Frankly, I totally agree that it might not be Top 3 when you include shows that are basically a single arc like FMA: Brotherhood (masterpiece). But when you start talking about the long form shounen with multiple arcs and progression like One Piece, Naruto, Fairy Tail, Seven Deadly Sins, Bleach, My Hero, etc., I would really challenge you to find three shows that are better than HxH.