I use the pegasusq governor. For me it gives the best combination of performance and battery. If it's more performance you're after I'd go for lulzactive.
I've never used the built in power saver so I'm not sure whether it lowers the clock or lowers the voltage on each clock step.
You've said you've rooted other devices so I guess you know about nandroids and app backups. There is however another important backup to make which is specific to Samsung devices. This doesn't happen often but it has been known for the efs folder to get wiped or corrupted when flashing so it's vital to back this up. If anything happens to the efs your imei will be wiped and you won't be able to get reception. It's pretty straight forward to backup. Download this app from the play store
https://play.google.com/store/apps/details?id=net.hellcat.droiddev.ktool&hl=en
Open it up and press backup efs to sdcard and then run the check and then you're done. Make a copy of the backup and save it on your computer just in case the original gets deleted. If you should ever need to restore it just use the app.