Taric is good but he has weaknesses.
Thing about taric: single target impact. He has a single target heal and a single target stun. Other than that, he is a walking aura (a good one, though, giving armor, armor penetration and damage if you count both W and R).
1) He has no mobility modifiers, nothing to help you retreat or chase.
2) He has no aoe cc like sona, alistar, leona, nautilus.
Those points matter alot IMO not so much in laning, but in team fight phase - if for some reason your team gets initiated on or is losing a team fight or you need to retreat, taric doesnt have much to turn it around - a sona, leona, ali make much more difference there.