You don't have to fly much to know some seats are better than others. I wish I could afford to fly first class everywhere. Aisle seats let you stick your legs out when nobody is coming by and so you get more legroom. Window seats let you see outside. Seats near the engines can be loud.

I long ago decided I'd pay extra for economy plus (or whatever the airline calls it) the cost isn't much more and the legroom is nice. My wife doesn't care (she is short so doesn't need legroom)