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