Aimpoint would be my choice. The reason is there is nil paralax which means that when sighted in if you throw double to your shoulder and the dot appears to be off centre in the scope but is on target, you are on target. They are a rugged unit.

Some of the HUD sights like the Ultra Dot- not saying is the case with the UD as I have not looked through one- can be very finiky. That is if your eye is not dead centre you can not see the display.