"Meanwhile,
Megadeth's still going strong." Well, this is a thread that aged well.
Metallica is no longer the one with whiney disagreements about how the band is falling apart, too.
As I'm sure is true of many of us, I could write books explaining my thoughts about every individual point of comparison between the two bands, not to mention the constant tension between loving and hating them both. On the one hand, they were formative for me, they were formative for metal, they've hosted some incredible musicians, and at their best, each was good enough to genuinely warrant most of the hype they've received over the decades. I have no qualms whatsoever about considering their defining works as among the best and most important that metal has to offer, and on those occasions when I feel like listening to them, I still believe that there is nothing out there quite like "Disposable Heroes" or "Holy Wars."
On the other hand, they're both overplayed, much of their material is overrated, neither has done anything of remarkable quality in years (unless that quality was "bad"), and at this point they're rock stars rather than actual bands. They're as much legacy acts as
KISS, and while they're more popular than ever, they've never been less relevant since they debuted. At this point I can't take them seriously - because of their own personalities, because of their inescapable presence in media (and in
the media), because of how exhausted every possible topic of conversation has become. Generally, I prefer not to think of them at all if I don't have to, just because of all the overexposure to their music and their drama.
Given the choice, though, I'd take
Metallica. I prefer their classic albums to
Megadeth's classic albums, which have always been spotty and unfulfilling to me, and their post-classic material has always been more interesting to me than
Megadeth's. I like James's voice in the '80s a lot more than Dave's voice in the '80s and I've found them about equally unlistenable since then, which is probably how a lot of those comparisons will work out.