Question [Q] samsung S3 GT-I9300 - jelly bean & ROM

Hello All,

this is my first thread in the forum and i also new with android

I've just got my new Samsung S3 device (GT-I9300) and i rooted it successfully using one of yours wonderful guides.
my current android OS is ICS 4.04 and i would like to update it to jelly bean.
I've heard that the most "clean" ROM belongs to Google and called "Vanilla" - is it right?
if so, where i can find jelly bean with that ROM? i've found jelly bean with "vanilla root box" ROM and i guess
that is not the same as Google.

Thank you so much for your help.