[NAME]  Happy to help.  I'm confused by you saying "I mostly use the extended monitor as primary (close the laptop)".  An "extended monitor" implies that there is some other primary display involved, and even saying you use it as primary suggests that there's still some other non-primary display involved.  Do you mean that you use the external monitor as the only display?  If so, then you can get whichever display you want, because if you'll only ever be using one display at a time, then you won't have to worry about mixing scale factors.  But if the two displays you use one at a time still use different scale factors when they're active, then you may have to log out and log back in when you switch displays if you want things to look their best.If you want to use the external display and built-in display simultaneously though, then that 225% scale factor will be a problem.  Running a 27" 4K display at 225% will give you an amount of workspace equivalent to only 1706x960 pixels, which less even less than 1080p (4K at 200% scaling gets you the workspace equivalent of 1080p, just with sharper graphics).  Yes, in theory you could change the scale factor of the built-in display to match the external display, but that would require lowering the scale factor on that display, which would make things smaller -- possibly too small to be comfortable to use.  Like I said, a 27" 2560x1440 is typically used at 100-125% scaling, and using that on your built-in display would not be practical.So I would say that you should probably plan to use only the external display when you're connected to it.  And in that case, you can go with whichever display you want.
Hi,  I would like to upgrade the monitor for my XPS 15 9500: Here my XPS system's configuration: The system is mostly used for programing, little bit of gaming and some video/photo editing as (hobby). I need help in selecting a 27" monitor that will work great with the laptop: 1. Should i go with Dell P2720D or P2020Q or else? 2. Someone suggest Asus PS278QV, is this monitor a good fit? Please help with any suggestions. Thanks!
P2720D or P2020Q for XPS 15 9500