As for "best" versus "favorite" generally, I think that is a fairly meaningless and fuzzy distinction. In any event, given that our musical preferences are not THAT different, if everyone in this forum votes for what they genuinely believe to be their "favorites" -- i.e., the albums they keep coming back to, as opposed to a particular flavor of the month -- I think we will tend to converge on shortlist of albums that most if not all of us can consider to be at least among the very best. And I predict that, not coincidentally, our list will end up looking a lot like the "best ever" lists you see in various publications or online polls -- albeit somewhat skewed toward albums on which Bruce Dickinson is the singer.
The albums widely regarded as "best" tend to be my favorites, within reason. So sue me. That said, there are many albums on "American (s)hitlists" I don't care for and think are overrated. (See "Dylan, Bob" and "Springsteen, Bruce." ) I apparently love
Mob Rules waaaayyyy more than anyone else does. Ditto Blind Guardian, Accept, Tom Petty, early Radiohead, The Clash, The Stones, and others. That's just me. Plus, my tastes change with my day-to-day moods. Though I love Queen, sometimes I'm more in the mood for Fleetwood Mac. Though I love Maiden, sometimes I'm more in the mood for AC/DC. There are also many albums that I enjoy for many different reasons unique to myself, like everybody else. But even though there isn't a clear set of objective criteria, I think people generally have an innate sense for what is "best." I include myself in that group.
Then there are some people who are overtly contrarian -- "I will find reasons to dislike Led Zeppelin because everyone else thinks they are so fucking great." (Talkin' to you, Foro!) That's fine -- as mckindog points out, the beauty of these polls/games is that we trend toward a consensus, so an individual's unique preferences get marginalized. You have every right to tell me why I'm wrong, just as I have every right to tell you why I think you're wrong. That's what's fun about these threads. It's like the Jordan vs. LeBron debates -- there is, in my view, an obvious correct answer (Jordan) but enough people think otherwise to make it at least discussion-worthy. Just don't get mad when I tell you I'm right and you're wrong.