Good mapping is quite vague so I would say something along the line of "consistent micro and macro planning of every aspect to a beatmap"
For example I think tengaku plays like shit, but it's consistent in terms of rhythm, aesthetics and flow, to which I say it's a good map, and I still play it from time to time even though I don't like playing it.
For example I think tengaku plays like shit, but it's consistent in terms of rhythm, aesthetics and flow, to which I say it's a good map, and I still play it from time to time even though I don't like playing it.