Is there something wrong with GOG's Bestseller List? Whenever I enter the site it's always Witcher 1 / Witcher 2 / Gothic 2. That's weird.

Well, it's nothing wrong, Witcher 1 in two weeks has become 7th best selling game, and Witcher 2 has become 8th best selling game, both sold better than Baldur's Gate 1/2 or Heores of Might & Magic 3.

And they probably counted Gothic copies picked up by those, who had possibility to choose one of the games when they were buying Witcher 2.