A lot of official game art comes through the inboxes every day. Produced by game developers and distributed by their public relations teams to the media, eye-catching official game art is the stuff that magazine covers are made of and are often posted on sites like this. They help build hype for highly anticipated titles that are in the early stages of development before the dissection of screenshots and additional details in previews that inevitably follow a game's announcement begin rolling in. Because so much is riding on the public's initial reaction to them, this sort of official art tends to look great.
But more often than not, it's fan art that GamesRadar likes best. There's something about excellent fan-made tributes that satisfies in ways that officially sanctioned game art can't.