Even SkyTeam might work, depending on where he tends to go. AF and KL have good networks in and around former colonies. It really depends on where he plans to go, and how much of a draw loyalty has over convenience.

If flying discounted Y, it is also good to check earning rules. In OneWorld, the lower fare classes on CX, BA, QF and IB generally less than 100% mileage credit, and Star Alliance is generally even more restrictive (looking through the ticketing carrier to the operating carrier, which AFAIK OneWorld does not). The US SkyTeam partners (CO, NW, DL) all still seem to offer 100% mileage credit (albeit not necessarily EQM) even for discount economy.