Usablenet is leading in Top 100K Sites and Top 1M Sites.
Usablenet has better usage coverage in more websites categories. Including Shopping, Business & Industry, Clothing, Consumer Electronics and 23 other categories.
Vertster is leading in Computer & Electronics, Computer Hardware, Relationships & Dating, Search Engine and 6 other categories.
Usablenet is leading in most countries, including United States, United Kingdom, Italy, Spain and 7 other countries.
Vertster is leading in Australia and Finland.