My two top tips are install Franco Kernel no matter what rom you're on. And go into Developer Options, "select run time" and change it to ART.
Your grouper will be the opposite of sluggish!
I'll upload Franco Kernel for you. Just dirty flash it in recovery and reboot and feel the performance.
When you switch to ART, the 1st reboot takes forever, don't worry, it's worth it.
As for best rom, imo it's Validus 5.2, I'll drop a link.
Omni is cool but doesn't have a theme engine, Validus has the cool things like Expanded Desktop, Omni Switch amd slim pie so there's no need to waste screen with buttons✌
Franco r79
https://app.box.com/s/v02obrjh1w4h7jbqb140 if it won't flash let me know n I'll give u an earlier one but honest, do a benchmark before and after and you'll see the difference.. Then activate ART and see your tab supercharged
Here's the rom, Validus 5.2 n its beautiful.
https://app.box.com/s/eqswa1brwxaaknpz73ct
Obviously make a backup first, do a full wipe, flash Validus then gapps, then Franco then restore your apps, activate developer options, "select run time" ignore the warning and the tab will (in about 15mins) boot into a 2014 device