Right now I like Taric, but he can be so useless sometimes it hurts me (because I still like him) his abilities scale with AP, HP and Armour, it makes optimisation really hard. I typically build 2 HP items (righteous glory, Sightstone) then MR and HP (merc treads and iron locket) while maxing W and with many armour runes. This does not make him as strong in combat, but his support traits are massive, and then one Frozen heart with the 20% CDR and he suddenly jumps in strength (from 140 to 250 armour minimum) stack a sunfire on top for even more hp and amour, plus dmg over time and he can just sit under turret while healing himself and smacking it down
But his flaws are not his builds, it's his kit, he has no MS, his stun wears off faster than it takes to land, leaving the window to utilise it stupidly low, (and i have twice stunned an adc attacking my turret, but the animation continues, then the stun wears off and its essentially like I didn't stun them, like a strange bug)
Taric can skill an adc often as fast as they can kill his adc. Problem is, if they kill you adc, they often run away (run passed you, kill adc, walk away) and taric can barely do anything. He does more damage but can NEVER catch an enemy once they have decided to disengage. He's only really strong when the enemy is foolish enough to stay and fight (like a jynx I beat recently 1v1 because she thought she would out damage me - but with my build I still had half my hp by the time she realised she should run, and could ulti twice).
When the enemy is low, its hard to catch them, unless you have long range cc adc like jynx, or speed buff from Sivir. If your adc gets ganked you can't stop the enemy, because you stun is so short lived and slow, that even if you deal more damage, they will escape before you can finish them, and you'll die if you chase.
Sometimes he wrecks, but sometimes he just stands around watching, unable to get involved. I spoke in another post about 3 changes (only one needed) to help him out.
He needs a speed buff ability
A longer stun on E
or his ultimate should be a mini-dash
Also considering his Ultimate being a knock-up (which would make sense) or it should radiate a slow.
He needs at least one more reliable CC, even if its an on hit slow from his passive (reduce the damage maybe), a slow with his W, or his R, but to be honest, his other skills are so balanced that it seems like it would break them. I think his weakness is his stun, it's slow moving and doesn't last very long.
If I was to suggest one buff, it'd be this:
When taric Stuns a target he marks them with "dazzle" debuff
while dazzle'd the enemy is made visible, and Taric gets a movement speed buff while moving towards them (something good like 25%)
this would give some chase potential, but not as strong as say Leona, but also give defence potential, by stunning a jungler who dives on your adc, you get a speed buff back to ally (a weaker concept for Braums dash)
If giving Taric a chase is too strong, and making support only is the idea, then giving him the ability to dash to allies in some way (utilising heal as well) would help him fulfil his role, cause right now, enemies just jump passed him, and if u stand behind adc, then you can't protect them from skillshots :/
increasing allied movement speed to targets hit by dazzle would fix tarics biggest weakness in my opinion, without breaking him like a knock-up ultimate or longer stun might