I am biased towards Shion because I think she's more interesting of a character. Mion might actually be the blandest Higurashi girl.
I like Shion more as a character, but Mion is cuter.
Shion is prettier and has an adult charm, Mion is cuter because she's a dork
I agree with >>182
, Shion's all grown up already and lost whatever childlike innocence she may have had. Mion still retains it though.
Shion. She's the type that makes you want to hug her and tell her everything will be alright. That's moe, isn't it?
Mion's not that pure...she already lost her handholding virginity