I have a bunch of rifles with Leupold scopes, but I decided to try something different on my M&P10. I put a Weaver Extreme 3-10x 50mm with illuminated duplex reticule. I am impressed. Large exit pupil, 3.2 inch eye relief, bright bright image, resettable controls, side focus. All this for $399. Now I don't know how many seasons it will hold up, but so far so good.
On my Remington 700PSS I have the big Leupold 6.5-24 with target turrets. Very nice scope. Cost twice as much as the rifle. But I fight with it every time I shoulder the rifle. Even dialed back to 6.5, the exit pupil is still small and requires contortions to find the target. On a rest, when I have plenty of time to get settled, crank it to 24x and it is very good. But in any fast moving situation, I find the Weaver is much better. The big bright image is *right there* for me when I throw the rifle to my shoulder, yet with 10x available, it lets me see to reach out and touch someone. Since the M&P10 is more of a designated marksman's weapon than the sniper weapon a 700PSS is, I think it is a mistake to saddle it with a big sniper scope like the Leupold.