For me the original hardware feeling is the plug and play nature no configuring of files just to get it to run.
Once you have it hooked up you just plug in a couple of controllers 1 for you one for your friend and done you are playing the game.
The controllers themselves play a big part to how the games play also playing snes games is technically correct on an xbox one controller however when you compare it directly an original controller just feels better when playing Snes games.
Same for Megadrive games I like to play with an original controller.
I recently bought a retrobit Sega Megadrive controller and in theory it does the job but in practice I have to switch to xinput mode first by holding start and b for around 10 seconds.
Which again ties into more configuration.
There is also the issue of lag either from the software or from the controller itself now while I have done some configuration of emulators finding a suitable one for low lag and purchased low lag controllers when you don't want to worry about any of it original hardware is best especially for classic consoles on a crt again plug and play
Emulation is good but it's not fast
Also CRT TV's look best when playing classic consoles again plug and play