yeah imo archon is pretty garbage now because flash heal is (for some reason) super undertuned unlike last season. might be worth testing this spec with the same priest/holy talents and an archon loadout (with the apoth talent instead of halo dmg/healing) though
UPDATE: I now recommend 2/2 desperate times over 2/2 prismatic echoes based on analysis of my overhealing and overall cost/benefit of each; what I wrote about desperate times below is outdated
oracle is super strong because pom is super strong; it’s either my top heal or just under my mastery every game. also, despite being centered around aoe healing, the build doesn’t really struggle with single target pressure either, particularly because it gets a ton of serenity cdr from all the pom procs and apoth uptime (you’ll have apoth up for ~22-23% of every game) but also because it has oracle’s “oh s***” buttons.
desperate times, divine word, and divine image are all worthy talents as well, but I think the aoe and during-cc stability from all the pom bounces outweigh the below 50% healing from desperate times, the fact that you’d be wasting throughput by taking divine word without resonant words as well, and divine image’s relativity low healing (usually only 3-4% of overall in a given game) make the pom build the optimal choice. also lightwell is absolute garbage because 15 stacks are not enough for the <75% threshold and because the heal is pretty small anyway
holy isn’t on disc level or even rsham, but it’s definitely at least middle of the pack now rather than absolute 
tier like it was last season