I'm of the mindset that raid buffs are always the way to go for the min-maxing meta, so AST/SCH in theory. SCH's buff being less important in early crit stats, SGE might shine there (also because the Media Tour build makes it quite strong).
WHM is seemingly fine but I don't think its Glare potency can make the difference, rDPS wise.
And in terms of healing kits, it's difficult to predict without knowing much about the amount of actual healing needed. But I do feel what we know of WHM's Lilybell is a bit underwhelming / very niche compared to AST's rain of stars thing, or SGE stacks of shields spell.


The big unknown is if we are to see encounter design changes that would make a difference in how we rank healers. Because currently it is all about oGCD heals and DPS. But if we are to GCD heal more, perhaps things could change.