Mrcer, Mystical have an additional 1 stamina over Pristine.
Growly, make up your own mind, I will try to present some of the facts, hopefully without error!
It used to be that, for every 1% resil, you were 1% chance less likely to receive a critical strike. To me this would have been very valuable for a f2p.
Now your resil % represents the amount of damage reduction of an opponents attack. So 1.87% resil would reduce a 300 dmg attack by ~5.6 dmg. Make up your own mind as to how valuable this is.
Sure, some f2pers stack resil and get, idk, maybe like 10% resil. So on the above attack, a dmg reduction of 30. That seems pretty decent but you can only get this by sacrificing other stats such as stam, int, crit strike, etc. Again, your choice. Personally I much prefer the latter except perhaps for FCing, something which I do rarely.
Pristine also give more armor. I just did a few quick calcs, so perhaps take the following with a grain of salt, or confirm it yourself. My Priest has 540 armor that contributes 20.45% dmg reduction. Thats 0.0379% per 1 armor. Armoried a belf hpala that came to mind and she has 1330 armor for 38.78% dmg reduction. Or 0.0291% per 1 armor. So keeping in mind that it seems this varies depending on class and/or race and/or armor type (cloth, leath, etc), a difference of 71 armor between Pristine and Mystical translates into a ~2.1% dmg reduction FOR the belf hpala. Add this to the 1.87% contributed by resil and you get ~4% dmg reduction, or 12 less dmg on your opponents 300 dmg attack. I just realised this is starting to get laborious. >_<
So anyway, I'll admit that's a bit better than I gave Pristine credit for, but I'd still be taking Mystical any day of the week, as someone who tries to maximise/balance int and crit.
I'll also add that in some brackets players are able to get ridiculously high resil %es. This has $&}%^#!@*-loads of value to those players and sometimes I think its this awesomeness that makes some f2pers choose resil when "perhaps" they would be better served otherwise.
Food for thought anyway...
