Seat tilters. That's the biggest discomfort for me. The person in the seat ahead tilting back. If there was a seating section that didn't tilt, I'd take it. I'd even pay a little extra for it.
Exit row if you don't want someone reclining in front of you, or bulkhead if you don't want someone in front you. There's always First when you don't want _anyone_ in front of you.
Or when, like happened to me, you get involuntarily relocated from the exit row seat you paid extra for? (Without compensation, since it was done by the flight crew during boarding and not in advance. Thanks, Singapore Airlines!)
The summer I flew with RyanAir. The seats were smaller than the last time I flew but it was so much better. There was more headroom than on other planes and the seats didn't recline.
Some of the budget airlines have seats that don't tilt at all - I believe the default tilt is slightly more than normal, but they aren't adjustable, which is nice.
Buy yourself some 'knee savers'. My 6' frame is such that if Im behind you, you're already not going to be moving your chair back much, if at all, before my knees are in your way. For $20 now some jack hole is slamming his chair into some plastic clips instead of my knees.
The end result is the same either way for the person in front me, so I feel no guilt in using them. I also make a point to never recline my own chair.
I don't even bother with the knee savers. I just use my knees.
I'm tall enough that in coach my knees make full contact with the seat in front. I just keep them that way for the first half of the flight, and the person in front of me assumes the seat recline is broken.
And if they manage to recline anyway, I make sure to hold my food or drink or reading material directly above their head while I eat, since they're pretty much in my lap anyway.