My normal choice for birds in flight are the Wide AF modes. To the extent possible, I use Wide-Small, but will move to Wide Large if the bird is hard ot keep in the frame. The reason is Wide modes now incorporate closest subject priority - so as long as there is no obstruction, the subject has a very good chance of being in focus.
On the ground, I use Wide Small some of the time, but also use Dynamic. Dynamic has a little bit of emphasis on closest subject, but really is useful because it is more precise. Wide modes often pick up the foreground or a nearby stick or pile of debris. Using Dynamic still lets me have a chance to track some motion - such as walking on the ground. The capture rate gets pretty low when they start to fly but it is still possible.