Is there an official haggadah?
How does one version of a haggadah have authority over another?
Is there a most popular one, a controversial one?
Traditional editions of the Hagada all share roughly the same core text, and many surround it with various kinds of commentary and supplementary materials. The core text itself is authorized by tradition; in that sense, I would say that any edition that includes the traditional core text is qualitatively more authoritative than one that does not. Other than that, I don't think any particular edition or commentary would claim authority over any others. They're all parallel ways of approaching the core text and experience. So many thousands of editions have been published through the ages and around the world that it would be impossible to crown one as "most popular."