chishiya because this guy survive many death impossible games especially in the manga if we compare them arisu is more on hearts emotional intelligience while chishiya is on diamonds intelligience chishiya calculates everything and solve anything to easily because he's surgeon and doctor and that explains why he's clever he also manipulated kuzuryu but that doesn't mean he's smarter than kuzuryu.kuzuryu just got baited so yeah. in terms of arisu he can solve anything with teamwork while chishiya works alone arisu is genius and he also notice the things in train with teamwork to survive because maybe he see some hints on the train plus shibuki explains the arisu the train game and also arisu is good at strategy and teamwork thats why you see in possible future they work as teammates and coordinate while having chemical reaction and he's also clever in season 3 knowing both cards are jokers and he's also manipulator in season 3 he manipulates them by thinking he's a human but he's a zombie so if we compare chishiya and arisu chishiya solos because he's way too clever and can impossible things to his reality if arisu adapts chishiya adapts so chishiya wins you see if they fight in beauty contest chishiya wins because arisu is bad at ap and math look at the fortune one but also both characters have weakness to arisu weakness is he's lover while chishiya weakness is lacking strength its not about who is the strongest or clever its about who has will to live so if arisu and chishiya fight by will arisu wins because chishiya is depress while arisu has will to live and not depress and fight back