You don't really need a whole lot for a video card for most emulation but if you do get into stuff like Dolphin, PCSX2, Cemu, Citra, RPCS3 and upping the internal resolution of games on those emulators you will need something.
You didn't specify what your budget was but I would go with something like an Nvidia 1050Ti. This will cost under 200$ and will perform well with the emulators mentioned previously and if you decided you wanted some modern PC games to go along with your emulation it will handle them just fine at 1080p resolution.
If the 200$ price tag is too much then you could drop down to a regular 1050 (non Ti) which has less video ram but it will cost around 140$ on Newegg. It will handle your emulation needs just fine along with some PC gaming but for that depending on the game you will need to tinker with some settings to get them running smoothly.
If 140$ is still too much then you can drop down to the Nvidia 1030 which you can get for under 100$ which again will handle emulation just fine and should handle resolution scaling in the more modern emulators and some basic PC gaming, just don't expect miracles on the PC gaming side of things if you decided you wanted to get into that at some point.