Unless you're running the shaders then even the onboard GFX on modern Intel chips is plenty enough for MAME (at least on Windows)
MAME doesn't really ask much of your card unless the shaders are turned on, the only reason it fails so hard on some older cards / onboard systems is because the drivers were utterly atrocious.
Maybe if you're trying to scale up to a 4k display you'd need something 'not terrible' but even then I'm not sure anything non-shader related MAME does would push it.