Which fictional character you consider more influential to you: Hanekawa Tsubasa or Kazuma Kiryu?

As much I like both of these characters, I'd say the former one. Kiryu's general characterization makes for a very good "benevolent gangster" character despite his general invincibility, but on the level of more specific characterization, it really doesn't help that his whole character arc may be the thing that suffered the most damage from Sega's attempt at milking the series as much as possible and trying to find ways to keep him in the plot, possibly without any intention to deepen his character. I still consider him a great character to play as (he's the kind of "gangster" character that is both benevolent and still confident/accomplished, I'd rather play as him than any of the GTA characters), but there's a reason why I have expectations for Yakuza 0 - it being a prequel story means Sega is now forced to actually do something with his character, unless Majima will pull an MGS2 Raiden and he'll be the actual star.
Now in the case of Hanekawa: not as much in Bake and Nise (partially due to them being pretty basic/bare in the first place compared to later installments), but the two Neko arcs and her screen time in Koi did a really good job at building a character that is an outstanding individual in many aspects, but prevents it from becoming "perfect" in the bad meaning of the word via giving her flaws that are not only in-character for her, but both aspects are pitched with more than enough narrative honesty to make the character click in a way that comes off as more human than most people give her credit for. I really liked Monogatari S2's aim of making the show's world more "rounder" by Araragi not being the only PoV character of the show, and IMO this worked out in Hanekawa's case the best: it's only five episodes, but those five episodes of Neko White do a very good job at making her character come together and give first-hand context to her S1 actions in ways that tends to be not spelled out into your face, elevating her into the most complex/complicated and developed character of the series. To be fair, even at its worst Monogatari has a more snappy writing than a lot of other shows and S2 represents quite an improvement in the franchise's overall writing (for instance Senjougahara, or even Sengoku worked considerably better in S2 in general), but I feel that Neko White is where things worked out the most, and it's her character that is an excellent example for a harem (and anime) character that has much more complexity and aspects than meets the eye, not to mention having a "dark side" counterpart that legitimately has more effort put into its writing than most animu "dark sides" out there. Right, Persona 4...?