I have a 24" 60 hz 1080p and a 32" 144hz 1440p connected and tried MSFS on both.
The difference is night and day the 32" 1440p is massively better. I do however run the 1440p at 90% render scaling as I cannot see any significant difference between 90 and 100 scaling even in the glass displays and it gives a fairly sold 50 FPS with minimal stutter on my setup.