Patch 7.21 just nerfed Ardent Censor pretty hard, so enchanter supports ought to be less of a priority pick than before. That being said, I main support and have found a lot of success with specific counters (like Sona into lulu, or Soraka into any of the other enchanters) but if you play a lot of support then you should know how to play
.
If you can land the hook, you can counter any squishy enchanters in lower elo. Be really intentional about getting a level 2 advantage (don't do a heavy leash and proc your relic shield on the first wave of melee minions, and push for lvl 2 first) and try to get your lane ahead early. Crush your lane so that your adc is further ahead in damage items than their support is in healing potential.
If you're getting into higher elo, then
offers the same pick potential and more overall utility.
Basically, if you can't counter with a better enchanter, get ranged-pick-potential and crush your lane hard enough that they're behind for the rest of the match.