It really depends on your definition of stronger. For one....anabolic to androgenic ratios don't always necessarily tell the whole picture. When you look at certain steroids like halo that have an astronomical anabolic rating for example....that gives pretty much zero muscle gains, but nice strength.
RAD acts a lot like testosterone, and gives testosterone like effects. It seems to be the better of the two when it comes to strength as well as being better for cutting body fat and improving a better sense of well being and "alpha" in the gym. It Has phenomenal lean mass gaining properties, but LGD seems to get a slight edge for many in terms of lean mass. LGD is also awesome for strength but behind rad generally in that area.
This isn't set in stone either. Some people just respond better to one compound over the other. You really can't go wrong with either, but obviously the best thing to do is stack them. My favorite sarms stack is rad, LGD, GW, and s4