871 haste > 50%~ mastery > 15% Crit (unbuffed) > Mastery.
That's atleast what i do.
If you heal with less healers and people are usually dropping a lot and the other healers are fairly bad or people just dont move out of shit fast enough and are constantly low on hp then mastery would usually be better. I personally prefer mastery because its less rng and heal when its actually needed
Your earth shield uptime could be a lot better. I just took a quick glance over your logs and looked at your Will log. Noticed you only had a 30% Earth shield uptime, that's pretty bad. Also to help the raid you should be dropping Stormlash totem on cooldown, make sure you're not overlapping with another shaman. Saw that you only dropped it once that fight, definitely could have dropped it twice.
Besides that, I'll leave everything else to actual Resto shamans... lol. Just some small things I noticed.
Has some others have echo'd for 10 man raiding I would favour crit over mastery anyday, especially if you run 3 healers. I have found aiming for mastery is a bit wasted due to the raid not being low enough ,enough of the time, and especially when healing against a disc priest or holy pally.
Now if you were 2 healing every fight I would def then look at mastery however this is not the case for you.
The mana returns from critting (love surge in 10 man) you will love if you give it chance.
One other thing, water shield glyph is very good on fights where your taking enough damage to keep the proc going, there is a list somewhere however I tend to keep it on most of the time.
Nothing else I can see to really point out which is on comparison to the reforge suggestion above.
Keeping everyone happy is impossible.
Whats in the boX - Raiding Heroic/Mythic content without the drama.