I would go with FB and try to keep North America travel on NW so as to maximize potential upgrades. The low qualification levels are a definite incentive and FB Gold gives you ST E+ unlike DL/NW/CO or FB members living in the US. The only problem is, to my knowledge FB do not offer status match. There was a status match one a few months ago for UK based travellers but it was not extended across the Atlantic.
I usually have a high level of success (50%+) for op-ups on AF between YUL and CDG.