If your phone is rooted, you could have difficulties getting an OTA update. You could either unroot your phone from the SuperSU app or you could manually do a 2-step update to 4.1.2 and then 4.3. Unrooting should allow your phone take an OTA update if you are currently on a stock ROM. For manual update process, please follow the instructions below ....
1) Go to the first page in the thread below ...
http://xdaforums.com/show....php?t=2387423
2) Download the 2 zip files under update412.zip and update43.zip respectively to your computer
3) Copy the zip files to a good quality (micro) SD card
4) Place the card in your phone and boot to recovery mode by simultaneously holding down the Volume Up, Home and Power buttons
5) Hold the buttons until you see a blue message flash across the screen. Then release the Power button but continue to hold the Volume Up and Home button until you see the Android image appear. Then release the buttons
6) Use the volume up/down key to scroll to <mount from external storage> and the power button to select
7) Navigate to the first zip file (update412.zip) and install. Wait for installation to finish and your phone to reboot.
8) Complete set up. Check your phone settings. Then power off and reboot to recovery again.
9) Repeat the process for the second update file.
The latest (official) Android version available for the i747 is 4.3 Jelly Bean. Android 4.4 (Kit-Kat) has not been rolled out yet for this phone so if you want the latest stock (official) system, that would be 4.3. If you are looking at a custom ROM, there are quite a few Kit-Kat based ROMs out there.