You have to decide if the interview question is honestly asking you to appraise your own programming skill, or else trying to determine if you a) lack self esteem, or b) have an inflated ego. If it's the later, I'd go with "4" (confident, but not egomaniacal). If it's the former, I'd go with a "5". Note that you're not really comparing yourself to all perl programmers, just those competing for the same job. If you were all being chased through the woods by a hungry bear, you don't have to outrun the bear, just the other programmers! (assuming the bear stops running while eating...)