> I ran across LCD
> monitors "Perfectly suited for arcade machines including MAME machines".
Those are typically old-tech underperforming, crappy generic lcd's sold by parts resellers who don't know anything nor care at all. Often not even full-hd, and TN-film in the worst cases.
Unless you get a G-Sync or FreeSync compatible (with either nVidia or AMD compatible gpu) all monitors are 60Hz period, whatever those resellers say. Eveything they pretend to be multi-sync blah blah blah is just the normal usually choppy framerate conversion and ugly scaling any normal lcd tv or monitor does anyway.
Focus on better and thoroughly tested and reviewed pc monitors, at least full-hd and IPS (or PLS) or even 'VA'-type (like AMVA) film.
Check websites like tftcentral.co.uk, pcmonitors.info, or even prad.de if you can read German, or overclockers.ru for Russian, there are more good websites Korean, Czech etc if that matters.
Also check NCX's recommendations on wecravegamestoo forums, very valuable advice here.
Models from LG, ASUS, BenQ, Iiyama, ACER etc dating back to 2013 year of release and successor part numbers/series are usually quite decent and in the same vein.
Everything in regards to framerate and upscaling handling will be done by MAME settings and your pc hardware together anyway, so again you just need the monitor that will best display a normal 1920x1080@60Hz period (or 1920x1200 or whatever native resolution your monitor of choice will feature).
> MAME isn't about playing the games anyway.