From some of the theorycrafting websites the stat priority changes slightly depending which one you are looking at and i just wanted to get some thoguhts on which one is actually the best to choose.
Icy Veins: Bonus Armor > Mastery > Multistrike > Versatility > Haste > Critical Strike.
Noxxic: Bonus Armor > Multistrike >= Haste > Versatility > Mastery >= Critical strike
My opinion: Bonus Armor > Multistrike >= Mastery > Versatility > Haste > Critical strike
The reason for having multistrike below BA (Bonus armor) is because Due to the change in death strike's heal it does not change dependant on damage taken in x period of time. meaning that it only gives a static heal. (Excluding Resolve). by tkaing multistrike this will allow you to be able to gain extra healing on average with death Strike's which counters all damage types (Excluding healing reduction abilities).
The reason for not taking mastery is because it gives a physical damage absorb %. This admitibly is very nice allowing the dk to minimise the spike damage he is receiving from incoming attacks BUT it is only relevent to physical damage.
In return i feel that having a higher chance for multiple heals from a ms proc on DS over a full boss fight would be more beneficial then having mastery as a top prio stat. But this does mean that there is a little more spike damage compared to a full mastery DK.. but if the DS are used at the right time and the healers are aware of this then the outcome should still be more beneficial.
Currently i am tanking with a bear who has 10ilvl's on me (540odd - 550odd) According to recount during the average boss fight i am still within 2% of damage taken but my self healing with this stat priority is 3/4 x higher (I know i am a dk).. i.e Bear = 3k Hps DK = 9 to 15k hps)
Even though i think priotising ms over mastery i still believe mastery is very important and thats why i feel it isn't far behind ms in importance.
PS sorry if i haven't explained my point of view very well..
If you have any suggestions why my theory is wrong then please let me know and i will change my personal stat priorty. thanks people