Gigabyte's RGB Fusion 2.0/20 bucks cheaper Vs. Aura Sync & ROG asthetics/30 MHz more Boost clock?
If you are considering about asthetics of your rig and it's ROG themed I think ROG is good to go.
But if you are not so interested in the looks of it, I recommend keep your 20 bucks. I think that 30 MHz might give you higher numbers, but the gap is so small that you won't feel any difference while running your games.
After all, their cores are same TU116-400-A1 chip.