I think that Slashdot has a niche that they stick to. Digg has grown wildly and as a result it is filled with crap that joe six-pack and his friends vote up. Slashdot values their core users, and it shows. They might not have as many articles or comments, but the comments on Slashdot are extremely insightful - i learn more from the comments on Slashdot than on any other social news site.
Slashdot really doesn't get it and as a result, it's becoming a ghost town. I used to visit Slashdot constantly. Now I look once or twice a week.
Digg, Reddit, and even YNews to some extent, can be filled with junk but they let me decide what's important, rather than what someone named Commander Taco finds important. It's the same as Wikipedia: give me all the information and leave the onus on me to separate the wheat from the chaff.
