As far as damage by position and type of counter, in general, Normal < Side < Back for position and Normal < Run Counter (Side) < Run Counter (Back) <= Attack Counter for counters. Tested with Astaroth's fully charged
- Normal hit: 65
- Side hit: 68
- Back hit: 71
- Normal hit attack counter: 78
- Side hit attack counter: 81
- Back hit attack counter: 85
- Normal hit run counter (side): 71
- Side hit run counter (side): 75
- Back hit run counter (side): 78
- Normal hit run counter (back): 78
- Side hit run counter (back): 81
- Back hit run counter (back): 85
Clean hit versions not included, as I have yet to find a way to make the system grant clean hit damage automatically (the way you can set counter damage).
Attacks that hit someone in the head (highs) don't do more damage specifically, as far as I can tell. I have yet to find a character with an attack that can be either high or mid, though.
Just inputs (inputting an attack using the fastest/perfect timing) will also increase damage slightly. This is separate from a clean hit.
Clean hits are apparently a pseudo-random chance of getting improved damage. There are some attacks that can increase this chance, and just inputs are said to slightly increase the chance of a clean hit.
Any of the individual elements stack (just input, clean hit, position, and counter), which makes a just input clean hit attack counter back hit likely the highest damage for any individual attack. How exactly they combine (i.e. is the whole greater than the sum of it's parts) remains to be seen.