As far as custom ROMs are concerned, there are 2 types- AOKP based and AOSP based. The CyanogenMod ROMs are AOSP based. The AOKP ROMs are also great and many people are shifting towards it. The AOKP ROMs are gaining popularity over the past year. The Nexus 4 owners will be happy to hear that Jelly Bean 4.2 AOKP ROM is now available for their device.