I've seen a lot of mention of Quark here, so here's my $.02. I've done plenty of press work, and use InDesign. Anyone who's had to deal with Quark can tell you that no matter what the "industry standard" is, Quark as a company is terrible. Why keep giving money to a company that continues to treat it's customers like they aren't the most important thing to it?
One argument for XPress is that service bureaus don't support it. Guess what? The service bureaus will support what we demand! If they don't support InDesign, find one that will and give them your money! I had the luxury of being a big account, and did just that. If there's demand, they *will* support you. Then we'll be able to flip the same bird at Quark that they've flipped us for years.
Other than Quark, X is better at everything on a modern computer, IMO. The only argument against X is if you have a really old Mac, and can't upgrade. I hate to say it, but the rest of the community can't wait for everyone, and we'd be happy to have you back when you can catch up.
But as for Quark, let's support the companies that hustle to support us. Yes, Adobe waited too long for Photoshop, but they're here and so are a lot of their big apps. Let's reward that.