75 is fine. Anything faster than 60Hz is better for your eyes than say, a bright flourecent bulb at 60Hz.
At 60Hz nearby flourecent lights will make the monitor flicker. 75Hz and above is easy on the eyes. In my opinion you don't want easy multiples of 60 either (90 might flash every 3rd cycle of the lights, 120 might flash every other cycle of the lights, etc). That leaves 75, 85, etc as good options.
Monitors tend to last longer if you don't push the refresh rate near it's limit. My current monitor overheats on hot days at 85Hz, so I have it set at 75Hz.
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