It depends, how much do you want to spend?
If the Monarch is attainable from your price range, the valuable is second to none. Compare the clarity to the Vortex of the same price and there is no comparison. I just bought a 5-20x44 w/BDC at Cabelas for only $400 while they are normally $550, just a matter of a sale combined with a coupon. I think once you get much past that price range you have crossed the efficiency frontier and you get a lot less for each extra dollar spent IMHO.I would recommend the Nikon monarch first, I have been choosing these over Leopold for my last few scopes.