Yes to illumination.
Seeing and shooting out to 600 with a quality 8x scope isn't difficult for me, but I am at a higher altitude and the sun is bright.10X is definitely better. If you can swing 16x or 20x, then you can get good definition at those distances.
On a 14-16" AR, I prefer a 1-6 or 8x. For 18-20", I think a slimmer 3-18 would be pretty sweet. I'm currently running a Sightron S-TAC 3-16x42. MIL illuminated reticle, FFP, 25 oz, zero stop. The only downside is the turrets are exposed and do not lock. The prices are very reasonable for the quality of the glass and the features
https://cameralandny.com/shop/brands...iation=3114718