Installing a custom ROM is not as cumbersome as it once used to be., especially for popular handsets like the Galaxy S4. Firstly you have to root your device, then install a custom recovery which lets you swap custom ROMs of your choice.
Its important to remember that installing custom ROMs may void your device warranty or cause device malfunction or data loss if you do not understand the process. Please note that you will be proceeding at your own risk.
That being said we have put together a list of the best custom ROMs for the Samsung Galaxy S4. Try them out and leave us a comment on which ones are your favorites
Omega v9.0 Jelly Bean 4.2.2
The Omega Series of ROMs have been available since the Samsung Galaxy S II. It retains the TouchWiz look at feel while removing much of the bloat to make the device perform much faster that it does out of the box. The Omega ROM even includes features from Android 4.3, like the Camera app and useful tools like Flash support, adding sub-symbols to the stock keyboard and many more tweaks and helpers.
Download Omega v9.0 Jelly Bean 4.2.2
P.A.C True All in One ROM
Download P.A.C True All in One ROM
Revolt JB ROM
Revolt is a combination of the reputed ParanoidAndroid and CyanogenMod ROMs. It is based on "AOKP source with cherrypicks from CM," ReVolt offers Apex, Nova and Trebuchet launchers built-in, DPI scaling, the MultiUser option and many more.
Download Revolt JB ROM
FoxHound GearEngine 1.3 AROMA
The FoxHound ROM offers a TouchWiz free near stock experience with added bonuses like call recording, hacked default email app, stock Google keyboard, and many more nice little add-ons that will make your life with the S4 easier and your battery last longer.
Download FoxHound ROM
Galaxy S4 Google Edition AOSP 4.2.2
While the Samsung Galaxy S4 Google Edition gives you that pure stock experience on your handset out of the box. This AOSP 4.2.2 ROM allows you to convert your TouchWiz based Galaxy S4 into a Google Edition device
Download Galaxy S4 Google Edition AOSP 4.2.2
source - PhoneArena