We have a good supply of both Lego and K'Nex here. I agree with your comment on K'Nex manufacturing but add that it doesn't really matter. K'Nex seem designed to connect well and holdtogether well despite this (I'm talking about the rods/joiners, not their stupid Lego-like bits which are just horrid)

K'Nex and Lego are different and my kids play wth both about equally I'd say. They get used to build different stuff and they're both awesome :)