Don’t like TouchWiz? Perhaps you are a Google purist who only wants to use pure Google ICS stuff?
No worries, there’s a ROM for that, the AOKP ICS ROM for your rooted Galaxy S3 i9300 brings you “pure Google ICS” experience bundled with a ton of UI customizations that you won’t be able to experience on TouchWiz-based ROMs.
This is one of my favorite ROMs of all time for many of my other Android devices such as the Galaxy S2 and finally, you can experience is on your Galaxy S3.
There may be some features that don’t work on the Galaxy S3 though as not everything is compatible. For example, you will lose manual-focus on the camcorder and also burst mode on the camera. This isn’t too big of a deal for most people and you can always flash a TouchWiz-based ROM if you need that feature. (What I like to do is backup 3 or 4 of my favorite ROMs using ClockworkMod Recovery Backup/Restore feature so I can always flash back a ROM I need.)