For me, the days of trying to find sweet spots in frequent flyer programs is over. I think its best to choose the program on the airline you will fly most, so that the benefits of points and status can most directly be used (and as the programs are devalued / enhanced, the airline you fly on the most still will deem you valuable).

In my case, I've read Flying Blue is the best program in Skyteam for redemptions but because my Skyteam travel is mainly in the US, I use Delta Skymiles for the direct benefits (free checked bag, early boarding, miles for upgrades).