A bird should have proper legs like a mammal or a reptile so it can get around for hunting and breeding, and if it needs to fly, then some auxiliary wings. An eagle is a reasonable design, since it has substantial legs for hunting from the air, although it doesn’t walk well.
Geese should be embarrassed to walk. What sense does it make to be a bird that eats grass? Why not put wings on a cow?
Birds are really terrestrial animals just pretending to live aeronautically. Imposters, all. (Except raptors, perhaps.)
The ideal bird would be able to make its living entirely in the air, by intercepting insects the way bats do, or by filtering tiny organisms out of the air, as whales do from the water.
The basic problem with birds is that they are heavier than air so they can’t stay up all the time. The ideal bird would be about the same density as air. Then it could live in the medium for which it was designed. It wouldn’t need legs and I would feel better about that.