I agree with the knee-poking in the back as a huge annoyance...also, when people recline too much on a plane. Having long legs, it really gets irritating because my knees touch the chair in front of me if the person reclines too much...not fun for a 6 hr or more journey. Babies yelling also tops my list.
Couldn't have said it better, you got the top 3. We must travel some of the same circuits . On a really bad flight, you could even get all 3, with a little turbulence thrown in just to push you over the edge.