First time posting here so i apologize in advance for any possible organization mishaps.
I have always been frustrated for many years with the lack of certain/definite answers to the question of whether you should get Armor or All Res/Single Res, Edit : especially in terms of your specific situation ie: your current defensive stats
So i have finally decided to something about it and crunch the numbers my self. I will start with the chart that I created with a quick explanation of how to use the information in the graph, for those who just want the info and then go. I will then follow this with the math behind what I did for those who want to use it for their own ventures.
To start, the chart will show a ratio of armor to all res in the first column, and in the second, a value of armor that will determine whether armor will give you more toughness or All Res will.
To get the First number, simply divide your Armor value by your Average Resistance total
The second number will determine which you should get, if your armor is less than the number in the second column, then All Res will more beneficial.
However if your armor is more than the number in the second column than you'll want more Armor because it will be more beneficial.
If the ratio of Armor to All res is less than any number listed, Armor is what you want for sure.
And if your ratio is greater than any number listed, you need All Res.
Now for all those who enjoy math I will now go over how I got the numbers in this chart.
First we start with the Equations for calculating armor and all res damage reduction.
Armor calculation at level 70 = x/(3500+x) All Res Calculation at level 70 = x/(350+x)
Where x is the Armor/ All res value respectively.
We then need the derivative of these functions because they are pretty useless as is
Armor = 3500/(3500+x^2) All Res = 350/(350+x^2)
One problem faced when relating these two functions is there inability to be solved for intersect due to imaginary numbers, so i was forced to table the values of the functions in order to find where they intersect. In addition they would not intersect unless by multiplying the numerator by the divisor between your armor and all res, and even then they wont intersect unless it is between 9.9 and 10 a very small domain, with a very large range which required the use of very small intervals to capture precisely.
After this it was very tedious work.
If you have any questions post them below, I myself feel there are things missing from the explanation, however i just can't pinpoint it myself, and i will probably come back to this tomorrow and realize it, but in the meantime enjoy the chart that i put together and i hope it helps.