There is a lot to appreciate Hunter x Hunter for. Besides being a landmark anime in its own unique way, its refined storylines, although seemingly unrelated, weave themselves around a central focus (differing according to the arc in question, but serve to anchor the narrative in place). In order to generate such an elaborate composition, there need to be dozens of characters involved, each of whom forms an important plot node.
Another great thing about the series is that it has villainous characters who, on occasion, are known to support the good guys (only if it suits them, to be honest). Everyone in Hunter x Hunter is furnished with a unique set of motivations, desires, and a plethora of emotions, but not all of them are appealing to audiences. Here is a list of those that are.
10 Ging Freeccs
For the most part, Ging is a worthless father figure for Gon, having abandoned his son while he was still a baby. Nevertheless, he does show that he cares for his little one's well-being, in his own twisted way. Ging is quite pleasant to be around when he isn't barking instructions at people or demanding that his son visit him without an "entourage."
The honorable aspects of Ging's nature become evident during the election for the next Chairman of the Hunter Association (after Netero's death), where he explicitly informs everyone present that it will occur exactly as the deceased wanted it to.
9 Chrollo Lucilfer
Although Chrollo is invulnerable in many ways, he does have a large space in his heart for the Phantom Troupe. When it comes to protecting the group as a whole, Chrollo believes every member is expendable, including himself.
This sweet demeanor is starkly contrasted with many of Chrollo's actions, however, such as murdering the innocent Kurta clan, profiting by selling their unique Scarlet Eyes on the black market. As horrific as this sounds, Chrollo himself doesn't seem like a cruel person, or at least he doesn't act like one (but this could be a part of his innately charming personality).
After Kurapika satisfactorily completes his personal arc, he becomes considerably more relaxed and his company is a lot more engaging (and a lot less revenge-focused) than before. Interestingly, his compassionate spirit partially emerges when he learns that Gon and Killua are in danger, placing his vengeance on the back burner until they are rescued.
Later, upon discovering that the Phantom Troupe are as tightly bound a clan as his own, Kurapika begins doubting the moral high ground of his mission. Overall, very nice guy but with some hardcore anger issues.
7 Alluka Zoldyck
Alluka's case is an unfortunate one: A little girl "possessed" by some kind of Dark Continent genie over whom she has no control, but because of whose actions, she never gets to have a normal childhood (not like any of the Zoldyck children do, to be fair).
Alluka is the cutest when hanging with her big brother, Killua, displaying inordinate amounts of affection for him that she rarely shows to anyone else. In fact, even Nanika, Alluka's demonic alter ego, likes Killua because he does not, like the rest of his family, treat her like a disease
6 Leorio Paradinight
At first, Leorio comes across as a greedy man who wants nothing more than to be super rich, at least that's what he claims. He soon softens in presence of his new friends, at one point telling Kurapika that his actual aim is to use the Hunter "stipend" to finance his doctoral training (so he can serve those who can't afford most medical practitioners).
Another one of Leorio's winsome facets emerges in the form of his responsibility: Towards his pals, his ambitions, and his home, all of them receive the priority they deserve.
5 Killua Zoldyck
Considering his natural affinity for Nen-usage, Killua is a powerhouse in his own right, but he hates the idea of using his powers for evil (which greatly disappoints his brother, Illumi). While he isn't always polite to people he doesn't know, Killua is one of the gentlest characters in the series, as seen through his interactions with Gon, Palm Siberia, and so on.
Killua also behaves in quite a childlike manner at times, especially with regard to chocolate-based snacks. The way his eyes begin to glisten upon catching a glimpse of "Chocolate Balls" is impossible to not find adorable.
4 Isaac Netero
Isaac Netero might be the strongest human in the series, but he's also one of the kindest. At least as the Chairman, because he sure wasn't a very humble person in his youth and middle-age.
Netero's impish conduct combined with overwhelming power makes his character a bizarre but rather lovable mixture. Netero admires those who can rise up to any challenge, but he has a terrible habit of making said challenges impossibly difficult just to see how far his Hunters will accept his authority.
Meruem's love (??), Komugi is timid to a fault, so much so that it inspires the Chimera Ant King to become a better individual.
Komugi is incredibly unpretentious but often tends to consider herself not worthy of anybody's attention or interest, which Meruem finds quite vexing. Komugi's empathy extends so far that she does not even scream while being battered senseless by a hawk, because, as she claims, "it is too early, and I didn't want to bother anybody."
2 Hisoka Morow
The hero/villain blend known as Hisoka is quite the mystery — ironic, as he isn't really averse to sharing his life story (unless he lied about the whole thing from the start, of course). In general, Hisoka is quite detestable, as his desire for a good fight eclipses any pretense towards morality, chasing down Gon until the poor kid's nerves are fried.
Somehow, Hisoka emits a strangely likable aura, especially when he chooses to fight on Gon and Killua's side (during their Greed Island dodgeball tournament). Perhaps he'll end up a protagonist at the end, who knows?
1 Gon Freeccs
It's a bit of a cliché that the main lead of a work of fiction is also its most likable character, but there isn't anyone in Hunter x Hunter as captivating as Gon Freeccs. He makes friends in all given instances, rarely stops to wonder about what the other person might think of him (or even if they like him at all).
Gon is always spontaneous, which occasionally leads him into quite the mess when he blindly charges into dangerous situations. Regardless, he believes that everyone has a good heart hidden within them, however monstrous their appearance might be.