I am of the opinion that a manufacturer should build his firearm so the firing pin strike is in the middle of the primer.
While Bart has addressed concentricity and accuracy, something that is not well understood is that primer sensitivity changes due to off axis hits. The further the firing pin impact is from the center of the primer the more likely you are to get misfires/squibs. I believe this has other effects as well, based on the assumption that the ignition characteristics of the primer vary on firing pin strike.
If you want the most consistency from your ignition system the first place to start is a firing pin strike in the middle of the primer.
If I'm not shooting, I'm reloading.