As a former White Room student, Ayanokoji can crack university-level exams and even beat computers at chess. However, he doesn't come off as someone special and blends into his environment. And that's precisely why Ayanokoji would have the upper hand against Light.
Undoubtedly, Ichinose is one of the smartest characters in the series, and her intelligence was shown more in season 2. In the Cruise Ship test, she was able to see through Ayanokoji's bluff, and even though Ayanokoji predicted this outcome, it showed her incredible perceptiveness.
Ayanakoji has a higher chance of winning. HOWEVER. Light is a sore loser and hates losing and will go at him again. With his abilities of manipulation, his "perfect image" reputation and his connections with the police through his father, Light could use all that to his advantage.
That's why imagining another student can outsmart him is hard. However, it's his end goal – to prove to his father that the WR learning model is inferior. For now, Ayanokoji still deserves the top spot. Even though he might not have proven his skills on paper, he's the ultimate mastermind of the entire series.
Both have very similar traits ... though light is a little bit more psychopath.. There are differences in physical strength. So, Ayanokouji can beat him by luring him into a combat.
So, I would say Lelouch is ahead of Ayanokoji, and he can outsmart him solely on his wits.
The toughest opponent for Light would be Saiki Kusuo. Saiki possess psychic powers including telekinesis, telepathy, and the ability to levitate, Light would last seconds against Saiki. Saiki is a character that gets stronger the more his opponent thinks.
Kiyotaka took the entrance exams to enter Advanced Nurturing High School and scored exactly 50 out of 100 points on every subject. A few others heavily hinted that this act was done on purpose to avoid unwanted attention from the school, which he denied by claiming it to be merely a coincidence.
Thus, Kiyotaka Ayanokouji has an IQ of 243.6 which puts him in the extraordinary genius category. For reference, the IQ required to be classified as “Genius” is 140 according to MENSA and the highest recorded IQ is 228 which was scored by Marilyn vos Savant.
Kiyotaka Ayanokoji – The White Room's Greatest Masterpiece
Out of every student that went through the White Room, Ayanokoji stood out as the one with the best results. As a result, there is no White Roomer that is unfamiliar with the name Kiyotaka Ayanokoji.
2 Kiyotaka Ayanokoji (Classroom of the Elite)
As a former White Room student, Ayanokoji can crack university-level exams and even beat computers at chess. However, he doesn't come off as someone special and blends into his environment. And that's precisely why Ayanokoji would have the upper hand against Light.
He is an incredibly strategical and analytical fighter. Weaknesses: Kiyotaka, being a lazy person, would rather avoid conflict and not reveal his capabilities unless necessary. He also said that his abilities have diminished since escaping the White Room because he is currently in a state of rest as a student.
Yagami was able to deduce the 5th question of the Unanimous Voting exam, like Kiyotaka Ayanokōji did, to make a plan to expel Ayanokōji and Horikita.
Kiyotaka Ayanokōji
Kiyotaka appeared to be the most successful, talented, smartest and strongest student out of all of them no matter the ages neither generations with him alone had a huge influence to the facility.
At some point the instructors figure out why Kiyotaka is better than the others as he's able to remember every detail of his early life, this genetic giving him more experience making him a natural born genius.
Viewers often refer to Ayanokoji as a schizoid, psychopath, or sociopath due to his cold, dispassionate nature. However, on deep character analysis from the light novels, one can see that the more appropriate term is Machiavellian.
Ayanokouji can destroy an elevator with a kick. He literally used 30% of his power to destroy that elevator. Meanwhile mikey at full strength can't even destroy a car with his full strength. Ayanokouji at his max would obilerate mikey.
And he's strong, given who and how many people he took down. Similarly, if you remember his feat in the sport contest, he can run well too. So his physical conditioning is extremely good, and I'd imagine he's one of the physically strongest characters in the series, if no the strongest.
While Ayanokoji is undoubtedly brilliant and can read others very well, his weakness has always been his ego.
While this deception worked, Ayanokoji, after discovering Chabashira's true intentions and the fact that her threats were mere bluffs, decided to abandon Class D and stick to his old solitary interest. This became more evident after he called off his deal with Karuizawa to help and protect her.
Before passing, Soichiro saw his son's lifespan, proving to him that Light is truly innocent. However, Soichiro was unaware that Light had a Death Note hidden on him but didn't have ownership of it. As Ryuk put it, Soichiro technically died happy thinking his son is not Kira.
When Light forgot his power he forgot the taste. However when his memory returned, the want of power overpowered his emotions, thus changing him. Not to forget kira's high Pride. He believe himself destined to change the world, but in order to do so he must let go of his emotions, that will stand in his way.
So Light is more intelligent, but L is just better at being a detective. VERY LATE TO THIS, but L is smarter. In volume 13: how to read, it is listed that Light and Near have a 9/10 rating for intelligence, and L is listed at an 8/10. Although, the creator also stated that L is the smartest.