I was thinking in terms of using fog cloud on yourself to hide in while closing the distance to the attackers or fighting in it while obscuring yourself from the attackers. If you are in a Fog Cloud you cannot be seen by ranged attackers so they cannot shoot you. Same with Darkness.
It really depends on the fight. But I've never been fond to give disadvantage for my own party. It's a nice why to blind a cluster of archers. If a spell has a 120 foot range, I like to use it
Sorry, was thinking of Darkness for actually hiding in. The 2nd level spell. Not Fog Cloud.
Fog cloud is for the attackers since it removes their advantage.
But with Darkness you can.
1. Move in and out of to make attacks. 2. Stay in and all melee attackers get disadvantage. 3. Use to move on a position by hiding the team in the darkness cloud preventing range attacks from targeting them.