Exhaust or Ignite?

So I've made it from Bronze 5 all the way to Bronze 2 this season so far, I know not that impressive but I'm still proud, and I main support. My hardest choice right now is which summoner spell to take, either exhaust or ignite. With exhaust you get an easy way to shut down fed and hard to kill opponents but an issue for me is that I never really know when to use it in lane, it's either like I never use it at all because I never see the correct time to use it in lane or I just use it to early in fights and make laning phase harder for me. With ignite however you know when to use it and the only supports who can counter it are Janna and Karma, because they shield, both of which barely anybody plays in Bronze, so having ignite almost always guarantees winning lane.

Please vote and comment why you chose which summoner spell.