Many, including me say that there is nothing called a “best ROM”, bu there are some firmwares that make a name for themselves automatically. My favorite for the HTC One X+ is Android Revolution HD 6.2 which is amazingly smooth and the overall experience is much nicer ROM.
I have been running Android Revolution HD from quite sometime now and the experience has been absolutely rock solid. It looks and feels great. Mike1986, the developer of it and recognized developer at xda-developers has not included any of the bloatware that came with the stock ROM. Here are its features:
Removed software (CPU) rendering – full nVidia Tegra 3 (GPU) rendering
Fully optimized and tweaked
ROOT (su + SuperSu Permissions – Thanks to chainfire)
Unsecured boot.img
Newest BusyBox
RAM optimizations
System signatures check enabled for system security and safety
Improved virtual memory management
Speed optimizations
Enabled GPU UI rendering
Data, cache and system partitions mounting tweaks
Bloatware applications removed
All /system applications updated to latest available
All /data applications updated to latest available
Improved camera performance
Improved CPU governors performance
Most optimal system scheduler
Disabled kernel debugging for better performance
ZRAM ready!
Zipaligned (Improved RAM management)
Zipalign on boot (for user applications on data partition)
Fully de-odexed
init.d scripts (BusyBox run-parts) support
Auto init.d permissions set on boot
sysro/sysrw commands support
Excellent battery life!
Improved EXT4 performance
You can replace HTC boot animation with any custom one (or use ICS default)
OpenVPN support
4EXT Recovery (Thanks to madmaxx82)
Most up-to-date system files permissions
Adobe Flash Player support for Ice Cream Sandwich
Support almost 24h a day
To flash this firmware, you will need
Download the firmware from here.
HTC One X+ unlocked with htcdev.com (S-ON) or S-OFF
Custom recovery
Here is how to flash it:
Download ROM and place it on your virtual SD card
Flash boot.img from the downloads section
Boot your phone in recovery mode (vol down + power)
In main menu, select "install zip from sdcard"
Select "choose zip from sdcard" and browse to the location of Android Revolution ROM
You can use data wiping option in AROMA (optionally if coming from earlier version of my ROM, obligatory if coming from stock or other custom ROM)
After flashing process is complete, reboot the device