I mostly use my original machines + MiSTer, but sometimes emulate on PC too. Some other good options not mentioned here are:
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ZEsarUX: emulates a lot of other machines too and also has some interesting features, eg it's the only one I know which lets you remap keyboard (to keyboard) - crucial for some games which haven't got joystick support and use crazy keybinds.
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Retro Virtual Machine: major selling point of this one is the "reel feel" - minimum menus, excellent CRT shader by default, graphical tape deck with authentic sounds...it's very nice, my go to emu for quick launches
-Retroarch: this one utilises existing emulators but you can use the additional RA functions such as excellent shader library and extensive remapping capabilities