It all depends on how much you fly, where you fly, and how you want to spend your miles. Flying Blue probably has the most value of any program in SkyTeam, but that’s mostly just true for long haul redemption. Using Flying Blue for domestic US flights isn’t any better than SkyMiles.

There are also some trade offs using an airline program that differs from the carrier being booked. Schedule changes can be subject to award inventory availability and you won’t see much if any benefit from elite status.