I agree that upon initial inspection, all look 2 1/2, personally, I would age #1 as 3 1/2. And I would do so for two reasons. First, the tips of the 4th tooth are definitely worn down. Look at how sharp the tips of 5th and 6th teeth are in comparison. Second, the amount of wear on the first three teeth. If that buck is 2 1/2, those teeth would have been exposed for less than a year, and that's a lot of wear for a year's time.
By following the standardized rules of aging by tooth wear, all of the jawbones would fit into the 2 1/2 age category. But in my opinion, deer #1 is older than the other two deer.