If you are moving to USA, then I think AC may be your best bet.
- Decent earn/burn
- Decent *G threshold
- Lounge Access when flying domestic US
AC's FFP overall is great as I looked into it before. However, the biggest downside (at least for me) is fixed expiration of miles. This would prevent me from accumulating substantial mileage balance for premium award redemptions. Obviously, if OP continues to fly in paid premium cabins, COS & elite bonuses go a long (& fast) way of racking up miles.
LAX