I stumbled upon some interesting quotes. They were posted by Wildheart888 on detectiveconanworld.com and obviously thought up by Gosho Aoyama.
"When you have eliminated the impossible, whatever remains, however improbable, must be the truth." -Sherlock Holmes/Kudo Shinichi
"Is a reason necessary? I wouldn't know the motives for a person killing a person but... as far as helping a person is concerned, why should there be a logical mind?" -Kudo Shinichi
"Idiot...there's no win or lose in this...no higher or lower...there is always...only one truth..." -Kudo Shinichi
"A detective who corners someone with logic, but lets them commit suicide... is no different from a murderer." -Edogawa Conan
"Humans are suspicious and jealous creatures. When they see something perfect, they wanna find a flaw." -Hattori Heiji
"I'm willing to commit mistakes, if there's someone else who's willing to learn from it." -Hattori Heiji
"Don't judge from the outside, like any beautiful rose has thorns, the more a person appears nice on the outside, the more you should doubt the inside..." -Haibara Ai