Radiant Faith/Watcher's Eye Guardian, in need of advice

I'm gonna make one of those crazy good mana, ES, armour, int and str guardians with Radiant Faith node, Watcher's Eye with 18% of mana as ES while affected by clarity, lots Healthy Mind jewels and so on.

A lot of people use RF with this build, butI'm not sure i like RF for this my character. I might end up using RF anyway, but I want to use my legacy Aegis Aurora that gives me 4% of armor regenerated as ES, and without saffell's frame or phoenix shield it's more difficult to get really high fire res.

Are there other skills/spells that would be equally effective for such a build?

Never tried herald of agony , which, if i understand correctly, can be used as main dmg skill, but I don't quite understand how it works, would the agony crawler be your main source of damage? (just started playing again after a long break from PoE, so i'm a little out of it)

How about attacks/spells like molten strike, winter orb, or scorching ray. Would they be as effective as RF?

Would really appreciate advice from people with experience with this build kind of build.

If anyone has some, I can say what I'm aiming for. At lvl 85+ would like to be at something like be 15-20k ES, around 600 int and strength (with iron will), 10-15k mana and at least 40k armor, and as much life -> ES regen with Zaelot's Oath as possible, so that I can facetank almost anything.