There is another section about gearing up, and one about class mechanics how is this one different?
With most of the gear you get from the open world you don’t have much of an option to target it to any specific piece, so you end up collecting a lot of gear, what you wear for stats can make major differences in your raid performance and is an area that can be challenging.
The quick and dirty answer for open world and even very basic raiding is if you are not sure just put on your highest ilevel pieces and hope for the best, It should be good enough for your first raid, but if you want to go the next step you should sim your gear, because it sounds more complex then it is and I believe its less complex than trying to figure out stat priorities.
This is actually easier than ever with new websites that help with this, there are two you should look into:
It takes a few minutes to step and normally requires getting some add-ons but it makes selecting gear a lot easier and reduces how much you have to think about it, every new piece of gear is just a new simulation, but as it takes into account your talents you should ensure that you have selected the raiding build before you run a batch of simulations.