User blog:GimmeStarfoxWii/Exhaust vs CV for Supports

So this is a debate I've been having with my duo queue friend for a while. We usually go bot lane as ADC/Support and swap who takes which role (Leona+Corki OP) and whenever he plays support he wants to take CV instead of exhaust.

I'm usually open to ideas like this, but I just don't see how CV could be better than exhaust. Sure you get sight any area on the map, but it's brief and has a long cooldown. We have wards, traps, and sightstones for vision anyway.

Exhaust on the other hand is useful all game, helps fight the enemy ADC, shuts down enemies in teamfights, and is great for catching people out.

Whenever I or our friends we play with say Exhaust is better, he says that CV is better, and we're just not coordinated enough to use it right.

So my question is, what is your guys' opinion of CV vs Exhaust.