This 1996 version of Itazura na kiss is the original and in my opinion the best one.
Here's why:
Nostalgic: It's a blast from the past and a fun no frills adaptation of the manga. If you love and miss the 90s like I do then you won't be dissapointed with this version. Great stylish wardrobes from the leads. Kotoko and Naoki really can dress haha. The sets are great too. Before the popularity of the internet and cell phones, people had to actually communicate and hang out in person. That's all here. The nostalgia of the burger joint Kotoko hangs out in with her friends after school and even the Tower Records-esque store Naoki once stole a CD from.
The best Naoki:
Yes Kassy's Naoki is the best version of this character. He's not a robot or as cruel as the other versions. The emotions are all in his eyes. Kassy's acting is subtle and natural. It's clear Naoki loves Kotoko from the start and it doesn't seem like their relationship and his feelings just come out of nowhere. Naoki is detached and stubborn here but not a complete jerk. He's just a teenager that feels pressure and fears for the future.
Best Kotoko:
Sato's Kotoko is loud, funny, and annoying like her character is written, but this version actually has a backbone. She obsesses over Naoki but doesn't let him get away with treating her or his family like crap. You can see she slowly changes Naoki in a positive way and he starts to open up. Her character progression is nice in this version as well.
The best kiss scenes:
When comparing this 1996 version, the other adaptations don't hold a candle to this one. I'm specifically talking about the 2013 and Korean versions where Naoki kisses Kotoko for the 1st time to be cruel and lead her on. 1996 Naoki isn't arrogant in the first kiss scene or domineering. It's Kotoko who chases an upset Naoki down the street at night and tells him she's fed up with how he treats everyone and says she hates him. He then tenderly kisses her asking can she ever really hate him. It's the way these lines are delivered and the way Kotoko closes her eyes and kisses him back that makes this scene romantic and not toxic like other adaptations. Also, in this version Kotoko kisses Naoki for their 2nd kiss shortly after their first. And describes her kiss as warm and filled with love. Again it was another romantic bittersweet scene.
Chemistry:
All the cast have great chemistry and work off each other well. The two leads have the best chemistry and come across as believable. Also, Kotoko and her dad have such a great relationship. Their father/daughter bonding moments in the series were really sweet.
Best ost:
Seriously the soundtrack to this drama is so good and perfectly fits the scenes enhancing all the cute, sad, romantic, funny moments. I usually get sick of the songs that are repeated throughout a drama but not this time.
Bonus:
I loved the style of filming (very 90s) with closeups of the characters and sometimes exaggerated facial expressions for comedic effect. Another thing I loved was the opening and ending credits which I never skipped. It was cute how they had Naoki and Kotoko recreate scenes out of the manga and show the drawn version vs irl. Also cute the way Yuki was a sort of narrator of his brother's relationship with Kotoko.

All in all, I give this version a 10/10. It's a must watch!