Looking at all the deer pics! But here is another age that deer! (the 8 on the left side of those two images)

That's a tough one. He looks 5 in the first photo. He looks younger in the second photo, however, he appears to be the more dominant of the two bucks in the second photo. And the buck he's threatening is not a youngster, either. I'll stick with 5.

Mature....shoot him if you like him

Looks mature, I always have a hard time judging between 4&5 year old deer, you know your area better than any of us so if he is a good deer for your area then take him,

Both look like 3 year old's to me.