We see this type of "irons vs. red dot" thread a lot; enough such I should copy my canned response to save time in the future:
Either can work, and as they say, "there's no accounting for taste," but by design, red dot sights will offer greater precision than iron sights - and THAT is difficult for me to ignore when hunting game. I've killed the majority of my handgun big game with a telescopic sight, and I grew up hunting with iron sights, but once I discovered the advantage of red dot sights, I've been hard pressed to recommend or use irons. The only excuse is cost, which isn't a good excuse. None of this is meant as a condemnation of iron sights, but the advantages of red-dot sights over iron sights are real, and are many.
Red dot sights are available with reticles in a multitude of sizes; I tend to prefer 2-4MOA dots for hunting. 2MOA is a bit fine for low light, fast acquisition, but it does offer the greatest precision.
Comparatively, iron sights typically subtend over 15MOA, and often have ~3MOA of float of the front sight in the rear sight notch. If you're using a covering sight picture, that's a LOT of a deer's vitals you're covering, and even if you're using a 6 o'clock hold, it's very difficult to consistently place an irregular target shape - i.e. a deer's vitals - on top of the front sight without floating a few MOA one direction or another. Comparing a 2-4 MOA dot to a 15MOA+ sight blade with 3MOA float is a no-brainer.
Low light acquisition of red dot sights is incredibly valuable for hunters as well - which should be self explanatory.
Of course, there's also an advantage of "forgiveness" to single plane red dot sights. Game animals move, and very often, you'll find yourself following game with your sights, waiting for your opportunity. It's very common for even skilled target shooters to let their sight picture drift apart a bit as they follow movers, especially if the shooter has to shift position while on target. And of course, it's easy for hunters to get a bit of "buck fever" and let their front sight drift in the rear sight notch. Single Plane red dot sights offer "forgiveness" for these tendencies, since it doesn't rely upon alignment of 2 sights.
I'm honestly not a "lover" of red dot sights in my heart (they commonly look like a wart on an otherwise elegant firearm, and there's always an innate stigma about using "combat components" for hunting to get over), but I do believe in what they offer me as a hunter and shooter over iron sights. I have the comfort of increased confidence in the precision of my aiming system when I use red-dot sights, which I believe makes me a better and more ethical hunter.