Honestly I think food makes way more sense than production for crime. People generally don't commit crime when they're well fed.
That said I think the best method would be a hybrid between
and 
, rather than

and

or

. We would also rename Crime to "Stability" or something.
This would mean we don't worry about upsetting the balance of starting locations or any number of other issues that could pop up.
"Walls would be purely a defensive building then!" Well yeah. I don't think it's a problem that defensive buildings would be defensive buildings. I'd still build them because losing a city to a surprise attack sucks. Even as Tradition and Progress I'd still often garrison because it's good strategically for defense.
I think that decoupling defense from happiness is a good idea and offers more interesting gameplay choices.
Add in that this one actually serves a purpose: If you're really unbalanced and try to avoid working the 'basic fundamentals of society' people worry. This would encourage a well balanced minimum of yields, and scale even more elegantly.