If the idea of simming yourself is daunting and new, running yourself through this should be much more accurate than any template strings you find on sites and a good introduction for you.
https://raidbots.com/simbot
To give you an idea of what you are looking for, Mastery is our stat we want to stack most of, but if you don't get a balance of Crit and Haste to scale that mastery, it will eventually start losing in value over the other two. That is why weights that you find on sites will only be guidelines, as the true value will change as your stats change with new/different gear.