Which rom is the most Stable ?

Hi,

I would very much like to know what rom is the best for the S3 as i need to flash it on my dad's phone and i am only here for a few days before going home which is a few hundred miles away so i need to get this right before i leave.

At the moment he cant use his phone so i need a stable rom on his phone as hes too old to learn how to flash.

Any recomendations is greatly appreciated.