Unfortunately, resto shamans don’t work that way. A melange of stats allows them to perform exquisitely. With resto shamans right now, you first want to make a decision what fits you better: the mastery build or the crit build (read the rotation and stat articles if you want to know more). Depending on that, you start gathering pieces. In general: if it has mastery and crit it is great. If it is either mastery or crit heavy, it is also pretty good. But as we’re just gathering stats right now (start of the expansion), the intellect/stamina gain usually is pretty massive.
If you ask for stat weights here, or on Discord, I’m afraid people will tell you the same thing. We’re not a one-trick-pony. Our class shines in different situations (different types of damage taken and different group sizes) and traits (resurgence and deep healing).
Hopefully, this helps you to choose upgrades.