Is there anything more irritating than the guy who the second the plane levels off after take off just slams his seatback into your face?
I will recline my seat, but often only partially. I almost always check to see who is behind me and if it is a tall guy I will not recline. I do know what they go through (there are sometimes advantages to being short).
The one that really bothers me though is the droner - the guy with a deep voice who can talk about parts for his mechanized ball bearing polishing assembly for four solid hours - obviously to a person who couldn't care less because they never interrupt him.
I often think this guy is sitting right behind me because his voice is low enough to even permeate my brand new ear plugs. Amazingly some people's voices will just carry a lot farther than others - and he might be four rows away.
Other than that not much bothers me on planes anymore - with my earplugs & eyeshades.
Except that every flight I am on runs out of the meal (hamburger) I want just before they get to me, so I am always stucks with "healthy habit" snacks like hummous and raisons.