Guys/gals. I suspect you have had a lot of suggestions after experiencing the new incredible climb up Alpe du Zwift but surely The Stelvio Pass is an obvious addition - perhaps coming from the other direction and linking at the top with the Alpe. Then you’ve got an iconic French climb and an iconic Italian climb.
Alpe d’Huez gains 1135m while the Stelvio is 1558m to 1800m or so depending on route. So I guess they’re not that good a match to join up at the top unless Zwift builds in a 400-700m descent to the bottom of their version.
Since the Alpe zu Zwift extension people want more .-). How about the Zoncolan :p.