Don't mean to bump this thread but I just saw this question on Yahoo.com.
If you want to put exact numbers on it, here are some RIAA-based stats, from the bands' respective signature albums of the 90s:
- Dookie (Green Day) - 10x Platinum
- Smash (The Offspring) - 6x Platinum
- …And Out Come the Wolves (Rancid) - Platinum
- Stranger Than Fiction (Bad Religion) - Gold
- Drunk in Public (NOFX) - Gold
The person who made the list excluded NOFX because they "didn't have the same popularity" as the others. Though they're really not too far off from Bad Religion's Stranger Than Fiction in terms of record sales. But that's not the point; there's multiple variables that go into what makes a band truly memorable that can't possibly be assigned a number (i.e. influence, cult following, audience, etc.). Then again, the true meaning of the list is to appeal to the mainstream, and deliver a lineup of bands that would be most recognizable to the public, not necessarily punk enthusiasts.