Sensitivity: Aim vs Movement

I'm new to OW2, first season, Gold DPS. Sombra and Reaper mains. Depending on map/ game mode, will also run S76 and Torb.

What's more crucial: Lower sensitivity for better aiming, or higher sensitivity for flicking and engaging/disengaging? And keep sensitivity same across characters, or use the customizing feature for different sens? And any specific advanced settings to try out?