Red dot sight with the BIGGEST window?

[Starslinger]

One option would be a red dot sight that is an "open" or "reflex" sight, like the Leupold Deltapoint Pro, Trijicon RMR and there are several from Holosun and Vortex. When you look through an open reflex sight, there is only a thin ring of metal surrounding the viewing window - you can see everything downrange because there is no tubular housing with dials obscuring your view.