There are three scope makes that dominate in the mid price range. You hit on two of them, the other is the Weaver Grand Slam.
Each has its selling points. The Elite 4200 has a broad power range (4x), instead of being a 3-9 its a 2.5-10. Elite has the rainguard coatings and a very durable tube design.
The Nikon Monarch series has been very successful for Nikon over the years. Many Leupold fans have switched to Nikon because of there unsurpassed clarity and crispness. The Nikon is light weight and the most attractive of the bunch (if looks matter).
The Weaver Grand Slam has the best adjustments made (micro-trac), you won't ever have to worry about your scope losing its zero. The Grand Slam is also the newest of the bunch giving it the most recent design and coatings. Finally the Weaver has rubber accented adjustments with rear facing numbers so you don't have to raise up off the gun to see what power you are on.
To say one is better than the other I would really need to know what its intended use would be. For deer hunting in the south, I'd pick the Nikon for its clarity and low light performance. Elk in Colorado, you would be better off with the Elite because of its more durable design and rainguard anti fog coatings. If your target and varmint shooting then the Grand Slam for its adjustments.
They are all very clear and bright scopes. You would be happy with any of them.