Let's look at newspaper front pages from a recent big news day (Thursday):
I would post examples from The NYTimes, but they don't let you see previous issues of the paper online for free. However, as I recall their picks closely mirrored The Washington Post's:
The Washington Post
Top Story: Cyber-Attacks by Al Qaeda Feared
No. 2 Story: SEC Charges WorldCom With Fraud
No. 3 Story: U.S. Court Votes to Bar Pledge of Allegiance
The Los angeles Times
Top Story: 'Tweens: From Dolls to Thongs
One of the store mannequins wears a fringed denim skirt riding low on the hips and a top pushed high on the midriff. Another has shorts that roll down on the tummy and a one-shoulder top.
No. 2 Story: Pledge of Allegiance Violates Constitution, Court Declares
No. 3 Story: WorldCom Hit With Federal Fraud Lawsuit
The Los Angeles Times shows a consistent bias toward "Reader's Digest" type stories that are entertaining and give you something to gossip about but don't really tell you anything of value. I also get the sense that many LA Times reporters are really failed screenplay writers who can't let go of the need to create drama. However, they do occasionally print something worth reading.
The LA Times is owned by The Chicago Tribune , which puts even less original content on its Web site and is more "in-your-face" about pressuring you to subscribe.
I suspect Slashdot would link to The Wall Street Journal more often if the paper made more than 1% of its content available to non-paying subscribers. (I had a paid subscription to wsj.com for about a year, but I no longer do because it's just not worth that much to me.)
I'd like to read Le Monde , but the French refuse to publish an English version. Go figure.
All of Knight-Ridder's newspapers (The San Jose Mercury News , Miami Herald , Philadelphia Inquirer , et al) have been crippled by the "RealCities Network" which forces all of its sites to use the same content-poor, ad-rich design. The saddest story of the group is the SJMercury though, which has just fallen apart since the parent company began slashing costs and forcing the RealCities conformity on its once industry-leading site. The Miami Herald is an unofficial training school for future Washington Post reporters, but that doesn't matter if you can't find their content on the Web.
Slashdot doesn't link to the Financial Times often (ever?), though it's a great paper. It just doesn't turn out a lot of unique content that's of interest to most Slashdot readers.
Newspapers aside, Slashdot has linked to CNN and the BBC in the past, though not the CBC . ABC, CBS and NBC generally provide watered down news for people who don't like to read newspapers -- not Slashdot readers.
Slashdot often links to MSNBC , but I expect that will begin to decline -- MSNBC.com's founding editor (Merrill Brown, a former Washington Post reporter) recently announced that he's resigning after 6 years to pursue other, undisclosed "opportunities." The New York Times noted on June 12 (you'll have to pay for the archived version of the story) that he offhandedly mentioned that MSNBC.com is about to be swallowed by MSN for economic reasons. (In other words, Microsoft put its foot down and said financial concerns outweigh editorial concerns.)
The International Herald-Tribune writes some of its own content, but a lot of the paper is an amalgamation of New York Times and Washington Post stories.
I haven't read the Seattle Post-Intelligencer or the Seattle Times in a while, but you may find some good technology stories there.
Bottom Line: Slashdot links to a disproportionate number of New York Times and Washington Post stories because both papers' sites post a lot of content and that content is top notch. It also helps that they're among the most recognizable names in journalism, but the Slashdot system is set up to allow editors to pick from the best stories that are submitted, regardless of the content provider's brand recognition. If you read a good story somewhere, submit it -- the quality of the story is more important than the misguided registration policies of the content provider. And if I've missed a good site people should be reading, reply to this message and let people know.