Marktest is leading in Top 10K Sites and Top 100K Sites.
Observer has better usage coverage in more websites categories. Including Business & Industry, Computer & Electronics, Arts & Entertainment, Internet & Telecom and 29 other categories.
Marktest is leading in Music & Audio, Soccer, Religion & Spirituality, Newspapers and one other category.
Observer is leading in most countries, including United States, Russia, United Kingdom, Norway and 7 other countries.
Marktest is leading in Portugal and Poland.