Honestly i think both of them is dumb cause sasuke became evil only because his clan got killed while obito he became the most evil of the series only because he lost his love my opinion is obito is more stupid cause he just lost his love while they is alot of naruto character who have suffered worser than they still good person
first of all dont forget that Obito was an uchiha, so he lost all of his clan too U_U besides, we dont know the reason why he became like that yet and also, tobi isnt really evil..in fact this mooneye plan isnt really that bad, if you think about it, because humans really ARE unable to live in peace...the mooneye plan kinda is like huxley's Brave New World...many call it a distopia, but it actually isnt....cause thats the only way to live in peace togetherU_U
so my anser is sasuke is more stupid, since he doesnt long for peace but only seeks destruction and vengeance...but then again he has his motives and is more of a victim...