Does he have poor eyesight? Because that resolution at that size of a monitor will make everything (including text) look huge (good if your eyesight is poor) but also not very sharp (pixelated, bad if you have good eyesight).
I think the
BenQ GW2760HS would serve your father well. At this size of a screen I'd stay away from tn-panels and their viewing angle limitations. White/grey like on most of the Google sites will look different at the top of the screen compared to the bottom of the screen on a tn-panel.
The monitor I'm suggesting has a panel of the A-MVA variety. This will give you better viewing angles and much deeper blacks. It might be worth it to
make a request in the product request forums for the BenQ GW2760HE, it's the successor of the monitor and should be slightly cheaper.
tftcentral.co.uk's review of the monitor is well worth the read