Not gonna lie, the changes hit him hard and he is not so self peeling anymore.
However he seems to have a potential to shine harder in duo with jungler or flexq, because of the power of staff of flawing water in group stage.

I am delighted :)

Pleased to hear that!
U might love our Taric discord server
I am still working hard on taric toplane and I would love to chat with u :)
[edited by moderator]

Since there is presence of mind both solutions (mnanamune/archangel) provide overkill mana in lategame.
This extra mana from tear helps the most in early midgame, and feels like a gold wasted later on.
muramana doesnt really have better damage counterparts, but archangel can be easly replaced by rod of ages(another one too).
I strongly encourage to give up archangel as an item.
Muramana itself is pretty situational:
it pretty much doubles tarics damage midgame,
gives unlimited mana
is pretty cheap
heals from catalyst
As long as you can access enemies it is a very good choice for split and powerfarm gameplan. However, if u want to perform teamfights and dives, sunfire should be a better solution (especially after buffs next patch) since it makes u more tanky.
Taric cant deal damage in every draft. Try to recognise the drafts when taric will have really hard time to reach the enemy and instead of buying muramana, focus on making sure u can move freely in teamfight, not totally disabled by one or two disengage spells.

There is good reasoning behind that however u have to notice that manamune and archangel have totally diffrent scaling. Manamune is very useful instantly after purchase, while unstacked archangel is not worth the money spent.

If u want to go archangel stack tear first or buy it in very comfortable games.

Grasp vs pta reasoning isnt that simple.
Grasp serves well vs those who last hit most cs using melee autos. For instance, there is no big use of this rune vs aatrox. If u think u will fight a lot and often during laning this is an excellent choice.
Pta however serves well in longer trades, and helps a lot to burst enemy during ganks.
Vs ranged pta should be better than grasp, there are other runes worth to try out including glacial unsealed spellbook omnistone and aftershock