I don't have enough experience with various red dot sights to say which is the best or even the top five. However, I have a Vortex Venom 3MOA on a G40 and have been very pleased with it.
I have had the Vortex Venom for almost two years and it is still on the initial battery. The battery can be replaced without removing the sight, so no re-sighting in. I have shot extreme loads in 10mm, like 220gr @ 1300+ fps, and the Venom held zero. I like the 3MOA dot because it is still very visible and offers more precision at 50+ yds ... hunting distances. However, the auto-sensor for light levels can be an issue on any red dot. Shooting inside a dark blind at a target in bright sunlight the red dot almost vanishes. The Venom allows turning on the red dot WITHOUT the auto light sensor function ... me like!
It is waterproof, a HUGE factor for a 'hunting' sight ... freezing temps, rain, sleet, snow aren't an issue if you can keep the lens clear... plus anti-glare for low light and shooting into the rising sun.
Vortex customer service is great ... I needed the special mounting screws, no problem, fast ship, no cost ... I lost the lens cover, no problem, fast ship, no cost.