Marktest is leading in Top 10K Sites and Top 100K Sites.
Observer has better usage coverage in more websites categories. Including Business & Industry, Arts & Entertainment, Computer & Electronics, Internet & Telecom and 28 other categories.
Marktest is leading in Music & Audio, Newspapers, Religion & Spirituality, Soccer and one other category.
Observer is leading in most countries, including Russia, United States, Netherlands, Japan and 7 other countries.
Marktest is leading in Portugal.