Well, it's subjective, for one thing, and for another (admittedly a slight reiteration of the original point) I kinda hate how those sets look, personally.
Mask of life when ever I see it I can only see Mata Nui so if your not building a Mata Nui Moc it's hard to see anyone else but Mata Nui
The inika masks are pretty hard to work with, since they force you to use those weird 2006 heads.
I actually built a decent Shrek head with the 06 cranium by flipping it upside down and reversing it. It creates a perfectly rounded jaw.
I think the toa masks that came with the beasts I mean black/white + trans neon yellow?
red is also a thing u know
I'd say any Nuva mask and the olmak