i saw a lot of new post/images/threads/reddit stuff about how to pair a support with the adc meanwhile you counter the other couple. as you say the answer you're looking for is hard to put in simple words since LoL is a RTS (real time strategy). so i make my choice according to my team comp instead of trying to counter only my lane. but without leave my early game open to my enemies.
so.. first of all you have to think on this:
- cc (crown control)
you can think on any champ that give you cc, from hard one like leona, zyra, malph, nunu, etc.. to soft one like lulu, taric, zylean, morgana and so
this fit with leona, taric, nunu, alistar, malph, rammus, etc.
this one fit with, taric, sona, soraka, nami, kayle
on the other side you can even mix some stuff.. tank and sustain go for taric (and some cc). sustain and cc go again taric, sona, nami... tank and cc, leona, morgana, nunu etc.
you are good with poke/zone, nidale, zilean, zyra, lulu
your adc is mana drinker and need sustain, soraka, sona/taric with mana manipulator
so, again.. is hard to say.
so again.. think in mid-late game, think in your team comp and what their need. dont forget your build should go on according how good bot and your team are doing (i.e. dont rush shurelya as first item if you are behind and go for aegis) etc.
another tip, one of the roles as support is you can deny a champ, so you should be able to play almost any champ as support, but remember that AP champs are better, since their skills scale better even if you have no AP on your build.
on the other hand dont forget to buy other roles champ, so you can trade... i.e. your team first pick want to play mid, but dont want to be hard-countered at the time you are last pick, so if you have some mid champs you can easily trade.
hope i help you.
see you in summoner's rift