Artifact Power Choices

[AngryLakitu]

So I've 62k AP stashed away that I'm looking to leverage the most efficient way to allocate it.

I currently play 3/4 specs: Resto > Guardian > Feral. I've reached a fairly comfortable spot on my Resto artifact and am now wondering where I should try and focus next.

Are there any clear cut winners that'd provide large gains in their respective trees?

Here are my breakdowns:

Resto @ 17 ranks w/ Dreamwalker & Tranquil Mind
Guardian @ 16 ranks w/ Embrace of the Nightmare
Feral @ 13 ranks (heading towards Ashamane's Bite)

To me, I'm thinking Ashamane's Bite seems like a clear favorite given the options, but are any of the available options in Resto or Guardian going to provide me a significant enough boost to warrant choosing one of them since they are, in general, my more dominate specs?

Edit: Guess I should clarify my playstyle/goals. No intentions of doing mythic raids. I don't play in a guild or with friends. I pug all my content and am currently 7/7 Normal and 2/7 Heroic. I've done some Mythic+5 and enjoy that system.