No consensus. See what it does, open up OCCT or voltage monitoring software + CPUZ and see what the different settings do. I have 0-100% options in increments of 3%-7% increases -___-; Had to toy with 0%, 9%, 35% to get a sense of what my mobo did to my CPU VCORE
LLC helps your motherboard maintain the set voltage, the higher its set it will push voltage slightly over your set while under load.
On my CHV asus uses different terms, you have the overvolt which is 100 for normal then 110, 120 etc. Maybe on yours 0% is stock for non-overclocked. Regrdless go up one step at a time while watching voltage on the cpu under load.
Not sure what your cooler is capable of but if you have good aftermarket cooling you can do a max of 1.5v safely for 24/7, many people I think say 1.55v max but I like to stay at 1.5 max and mine has been running good 10months which that voltage.
Helps reduce vdroop. Vdroop is the voltage difference between what you set in the BIOS and what you really get under load, LLC can help tackle that by reducing it or eliminating it as much as possible.
Highest LLC setting is not always the best, it will more than likely spike the voltage much higher which = less control over voltage and spikes (which can sometimes be dangerous, especially when playing with high voltages).
I would recommend that you try each of those out and see which setting controls the voltage better and reduces the vdroop as much as possible, I would probably guess 50%
With my Crosshair V, my LLC on Ultra High increases the voltage by one tick under load (0.012v). With it off, my voltage gets undervolted and with it on Extreme, it gets overvolted like mad. You basically just have to test each one and determine which one works best for you/how much voltage difference you want under load.