I can't vote because I cannot live by one wood alone. I variously use hickory, apple., cherry, maple and oak (and some times black walnut, pear and mesquite) I would be hard pressed to pick one wood.
I've always been a big fan hickory, but lately my go to has been pecan and cherry. Not so much for flavor but more for color. I can only tell very small differences in taste of different woods. Some folks can tell easily but I can't. Not sure why, but wish I could!
I also can not answer this question. I have not tried them all yet. I just had a friend give me two truck loads of apple wood so for a good while I guess thats what it will be.
Tough question. In my situation it all depends. Stick burner likes white oak and hickory. If what's cooking is in a charcoal cooker, then a combo of cherry and peach. If I had to pick just one it would be Peach.