The purpose of this thread is rather clearly stated in the title. Without further ado here we go:
Potency vs Tenacity
LevelDelta = clamped modifier based on difference between levels of attacker and target. 0% if the attacker is equal or higher level, 5% per level that the attacker is below the target, capped at 30% max (6 levels).
BaseUnitResistChance = a constant, set per Battle type. It could be different in Raids vs Arena and so on, but it appears to be a consistent 15% across all modes.
RealTenacity = displayed Tenacity - BaseUnitResistChance. Typically, that would be displayed Tenacity - 15%. The displayed Tenacity value includes BaseUnitResistChance as "fake" Tenacity and is not used as part of the Tenacity value when plugging it into the formula below.
Chance to Resist = max( 0, RealTenacity - Potency + LevelDelta ) + BaseUnitResistChance
The cap on Chance to Resist is 100%.
What does this mean: Tenacity higher than Potency does confer a straight increase in chance to resist. Unfortunately, the only viable way to actually do anything useful is to use a leader with high tenacity team bonus, and then also stack Tenacity mods.. you'll do less damage, but resist more effects.
Offense mods vs Crit Damage mods
Everyone has a compelling argument over which is better and why, but in reality the only blanket rule that you can apply to which mod is better is this: if the group composition gives a 20%+ crit chance bonus that will have large if not constant uptime, crit damage is better.
There are 3 things that most people don't take into account when comparing mods, the first is that what mods consider 100% offense is not what we would consider 100% it is less than that. 105.88% offense is the base that we call 100%.
The other is the fact that as you get more and more offense primaries and secondaries on your gear, the value of the offense set as a % of our in match damage decreases. This means that, in general, offense sets have a higher value early in game, but tend to decrease in value the closer you get to end game.
Finally, stats from gear equipped in the current level do not count towards base stats and must be subtracted before %es are calculated and added back in afterwards for a complete figure.
Bearing all that in mind, it's rather complicated which is better, and it really comes down to the other stats on the mods, and the composition you are using them in (Darth Nihilus leads will always prefer offense mods for instance). So I have come up with a formula that accurately compares a set of crit damage mods and offense mods to see which will result in the highest overall damage increase on average.
The long drawn out but entirely accurate formula on how to compare is as follows:
in match effects
crit damage set stats
offense set stats
100 / ((100 / (186 / 30)) * (100 / (Base offense - Applicable damage from Current gear) * (1 + total %offense from primaries and secondaries: expressed as a decimal) + total flat offense secondaries + Applicable damage from Current gear) / ((Base Offense - Applicable Damage from Current gear) * 105.88 + Applicable damage from current gear)) / ((100/(1 - (Base Offense - Applicable damage from current gear) * (1 + total % offense from primaries and secondaries: expressed as a decimal) + total flat offense + (base offense * .1) + Applicable damage from Current gear) / ((Base offense - Applicable damage from current gear) * 105.88 + Applicable damage from current gear))) - %Crit Chance increase from Buffs and Abilities = Critical chance breakpoint
Applicable damage from current gear is either special or physical damage on gear that you have equipped that you can still examine. Which one to subtract and then re-add depends on which type of damage the character uses.
If the crit damage set of mods you are examining has a crit chance above what the breakpoint is when combined with your character's base crit chance, then it is better than the offense set you were comparing it to as far as total damage output goes. If it is below it, the offense is better. If it is an exact match, then neither is better.
Figuring out starting turn order with turn meter gain
The formula to calculate the effective starting speed of a character who is getting tm gain to set a starting turn order is as follows:
Character speed * 100 / (100-%tm gain) where character speed is the character in questions speed according to their character panel + any ability bonuses (jawa engineer, Holdo, Vader, etc.), and the %tm gain is the amount of turn meter gain they will be getting due to whatever ability is giving it to them.
For example: Jawa Engineer is giving droids 45% tm meter to start. If I have my IG-88 at a 240 speed, that means his effective starting speed is 240 * 100 / (100-45) = 436. This also means that I need a Jawa engineer of at least a 437 speed to still be able to establish a starting turn order for characters with a speed of 240 or less by setting their speeds in descending order because characters with a 241 or higher speed all in this scenario all end up with 100% tm at the same time, which makes the order random.
Now the part about them all getting to 100% tm is a bit different with activated and triggered abilities. For example BB8 and Zeta Maul both give out some turn meter to start the match. When they do, the character with the higher speed will always go first to start the match. But with Jawa Engineer/ Sith Assassin/ Rex, etc, if the characters getting boosted are too fast in comparison to the one doing the boosting, the fastest character may not always go first. This means that one character getting boosted by the activated ability can be as fast as you can make him, as long as the next one is one below the breakpoint created by the tm gain guy.
This breakpoint can be calculated by flipping the fraction in the first formula:
character speed * (100-tmgain%) / 100 = speed breakpoint
So If I have a jawa engineer that is a 360 speed I get
360 * 55 / 100 = 198 as the speed I can only put one character equal or higher to still be able to establish a starting turn order.
Defense mods vs Health mods
I will fill this in once I locate the formula for calculating defense.