Or would a short crosshair with a gap in the middle work better?
Personal preference really.
As you know Reaper does his damage per pellet and gets his healing per pellet as well which spreads out.
So you want to have the max amount of that spread to hit your target. Which means you want to fire when your aim is in the centre of someone rather than it being off to the side of them.
So with the line or dot reticle you might find yourself firing as soon as your aim is on the side of your target and not in the center of your tagret.
But the same can be said for the circle, you might fire when the tagret enters the side of your circle in which means the center ot your aim is actually not on your tagret at all and you have missed more of your pellets than you would with the line or dot.
Or you might naturally try and fit as much of your tagret in the circle. In which case you would preform better. Which might help you if have an issue of firing when you’re too far away or too close from targets. The circle will show you the correct distance you can be from your tagret, where you will get the max amount of value from your shots.
The crosshair with the gab in the middle is typically used for snipers or heros trying to get headshots. The lines help you line up your own shots better, and when your tagret is moving around you can see that moment where their head is blocked by the crosshair and then reappears when their head is in the middle of the crosshair where theres a gab in the middle. But with Reaper, you aren’t going for those shots so. It doesn’t really matter.