Best test I and a friend have preformed personally in the past (2008-2010), is during low light conditions at the range (or elsewhere in the field) at dawn and dusk, to check resolution and definition of marks and lettering on targets at known ranges with the various scopes on my rifles, or friends. Many scopes will provide adequate resolution, but there are clearly those that out perform others.
Leupold has performed well, equal to the Nightforce; while Zeiss, Swarovski and Kahles have performed better. Scopes with similar sized objectives compared one to another, at same power settings. Best to date of those tested have been the older Kahles hunting scopes no longer in production (3-9x42 w/ TDS). Sorry, have not performed with newer or tactical type scopes. Have not compared my Kahles to my S&B, both 1.5-6x42 scopes,since acquiring them, to see which has better resolution.