Yeah, I don’t really take any stock in the ratings. It’s so subjective and impossible to rate this much content with a 1-5 star scale. Narrowing it down to that bleeds any and all nuance from each show. That’s why I started commenting on episodes in the first place. It’s not to let others know about a particular show, in truth, but to leave a roadmap for myself when I come back to listen because there are gems in each era, and duds as well.
As for best era…eh…hard to really pinpoint it. I don’t think I can narrow down a favorite era necessarily, especially if we’re just basing it on the ratings. I would say 2004 is strong, but I’m pretty sure that’s when Chief Thunderbear made his first appearance, and I could live my whole life and never hear a Chief Thunderbear bit again and be just fine. Also, 2005 is interesting because Adam really starts to let his frustration show, and the end seems inevitable. It’s a solid era but certain shows are tainted by that awkwardness, like sitting at the dinner table and dad reaching out and smacking mom. There’s really no going back from that.
I think in the overall scheme of things, this site proves what Loveline’s prime was, which was the Adam Carolla era. I know that’s not what you’re asking, but that’s my honest opinion of things. It’s all great from his first episode to his last, and it’s never the same after he leaves. Ranking all that went in between seems irrelevant.