At least with WN you can usually change seats pretty easily (if the plane isn't full or it's early in the boarding process.

BTW, I've had the "kick the seatback" problem on DL, AA, and CO, and I've seen folks get pretty snotty with the kids and parents on more than one non-WN flight. So if you think you'll avoid it by flying something other than WN, think again.

Worst experience I think I've had was on DL where a woman brought a cat (in carrier) on a TATL in the J cabin. The cat yowled for nearly 3/4 of the flight. Far worse than a kid screaming. Flight crew did nothing.