En Kolay Yolu: jelly

Jelly Bean ROM:Omega ROM For S3 i9300

We did mention it in our battery saving post,based on stock rom its optimized to be used as a daily driver,very well-known.

Please read the following before flashing v61:-

Make sure to make and keep in a safe place efs backup - nadroid backup - titanium backup - etc, in case you ever need to restore!
Full wipe is needed if you are coming from another rom or stock firmware or Omega 4.1.2 versions
If you are using CWM based recovery ignore "Disable Recovery Flash" and "Fix root (/system/xbin/su)" messages at all times, just select "NO", else selecting YES will break root.
If you want to change lockscreen personal message make sure to include Samsung fonts during installation
SuperSu: If needed open SuperSu and update SU binary, then choose normal and reboot device.

DOWNLOADS:-

ROM v61
ROM Torrent version

JellyBean ROM:NCS ROM for S3 i9300.

Made by @dkionline,this is a really simple outtake on our stock rom,the last being jelly bean.Its equipped with Boeffla Kernel by standard and is totally debloated and optimized.

This is a great rom especially when that stock nostalgia strikes you.I had thought about posting one,but did not find stable ones.And suddenly this pops up.

So here you go.