-- The scanlines artifact only shows on some monitors when their limits are being pushed (e.g. closer to their maximum refresh rates, or during overclocking, or when enabling strobe mode). It doesn't happen on all of them, and sometimes it's a panel-lottery behavior (luck of the draw) for certain model of monitors.
As far as I know:ASUS PG248Q
-- can overclock to 180Hz. Generally "scanline-artifact-free" at 144Hz and lessASUS MG248Q
-- Unsure, but probably notBENQ/Zowie XL2430
-- No scanlines issue as far as I know.
Be noted, I have heard many situations where for the same model -- A user had scanlines artifacts and another user did not. Sometimes it only shows on a specific corner of the screen, rather than full screen. A typical scanlines artifact looks like this: http://dhainne.free.fr/weirdscanlines.jpg
... Not everyone finds it objectionable nor distracts from their gameplay, while others are bothered by it.