Brightness, Blacks and Contrast
DisplayHDR 400 certification can be considered basic by today's standards, and while it's true the Agon's HDR credentials are middling without localised dimming, over 400 nits brightness is a fine fit for everyday SDR use.
AOC doesn't attempt to top the charts at the expense of overall cost, yet at £899 the Agon AG493UCX offers a sensible mix of good brightness, decent blacks and reasonable contrast. You do get some colour shift and black crush, as is to be expected given the inherent limitations of a VA panel of this size, but there are no major red flags and AOC has the essentials well covered.