I think the Green card has very limited appeal in a multi card strategy. I have an Altitude Reserve which earns 3x (4.5%) on travel (not as broad as Green, admittedly). It costs me $75 net/yr. I typically only get around 1.2-1.4cpp with MR so it doesn’t make sense to earn 3x when I can get 4.5% for a lower fee (I don’t find much of any value in the Green lounge buddy/clear credits).

Of course if you’re one of those folks that consistently redeems your MR for international business class to Asia and are getting absurd cent/point valuations, it could make sense.