The battle for audience supremacy in the online news category continues to be a fiercely competitive race between Yahoo News, CNN.com, and MSNBC.com, all of which enjoy a 25-30 million user range, 10 million ahead of the closest competitor, AOL, reports MediaWeek.

While ABC, CBS and Fox have all pumped resources into their online news operations in the last two years, resulting in increased traffic, none has cracked the top five among news sites in terms of monthly unique users, trailing the leaders by roughly 20 million users.

Meanwhile, as the category leaders jostle for the top spot, each cozies up to whatever metric serves it best - since, unlike TV, web advertising isn't necessarily reliant on ratings. Said MSNBC.com president Charlie Tillinghast: "On TV, they get paid on those numbers. It's more of a beauty contest on the web."

For example, CNN claims it wins on something it calls "share of online news," a metric that calculates each site's percentage of the category's total "gross usage minutes" using NetRatings data. And fourth-place AOL News contends that its smaller user base consumes more pages each month than Yahoo (an average of 40 to Yahoo's 32, according to NetRatings), and thus is a more engaged, advertiser-attractive audience.