An Avengers Mansion for X-Men heroes that only triggers half your turns but is half the cost (ok 60%). And that half of turns is only if you are flipping between hero and alter ego every turn. Some heroes like Cyclops and Colossus are happy to do that, but others that don't get much benefit from alter ego form might trigger Moira even less. Moira is definitely on the slower side, but card draw is always powerful, and Moira is cheap enough that you can probably play something else the same turn you play her to not fall too far behind.
Where Moira clearly shines is multiplayer, as even in 2-player you can get her to trigger every turn if both players are opposite forms. In a 3 or 4 player game, she should be almost guaranteed to trigger every turn, making her way better than Avengers Mansion. Between cards like Moira, The X-Jet, Danger Room, and X-Mansion, multiplayer X-Men teams are far stronger than the sum of their parts.