Unfortunately many emulators outside retroarch because they are mainly Windows focused, they are not low res friendly and have issues running at anything lower than 800x600 or even 1024x768.
That is a huge deal if you want to play on an old vga monitor. Newer Windows unfortunately blocked all resolutions below 640x400, requiring software and hardware shenanigans. On Linux you can still use low resolutions without any extra steps or external apps.
Out of the emulators I tested, the ones that run fine at 240 on Linux are Redream and Scummvm.
Every other emulator shows distorted images and unaccessible menus.
Though in cases like gzdoom, vkquake and nblood etc if you can skip the menus, games run fine at low res.
I use Retroarch mostly on Linux. There I also use Scummvm, Redream and Dosbox Staging. Staging provides the best and smoothest experience for dos games at 640x480 and 640x400 resolutions.
On Windows I use RA mainly for the shaders and the gsync monitor but because gsync also makes a difference in non-Ra emulators I use those too.
Mainly mame (arcade64 front-end), mesen, ootake, nanoboy, psp Gold, flycast, dosbox x and Staging etc
Also Sega model 2 and 3 with wide-screen and ultra wide screen support
But main reason is that I do not want to overstrain a 20+ year old vga monitor, so I use it sparingly,more focusing on Windows.