Cyclomatic complexity (which I think is the most common one used) also doesn't really map to what people understand as complex. A giant switch statement with on

Cyclomatic complexity (which I think is the most common one used) also doesn't really map to what people understand as complex. A giant switch statement with one return per case isn't nearly as complicated as two large nested if/else blocks. Nesting almost inevitably means more contexts you need to keep track of when reading code, particularly nester conditionals.