In the first pages of Dragon Heist, you're told to
When you run this adventure, you choose its main villain at the outset. Your choice determines the season of the year in which the story takes place, as well as the antagonists in several of the encounters in chapter 4.
While multiple places in the book specify you can switch villains at any point.
You can swap out one villain for another at any time.
If you switch to a new villain midway through the adventure, don't change the season to match.
The problem is, there aren't any guidelines to choosing the villain. I've read the first 3 chapters, and so far there are only allusions to Xanathar's and Manshoon's (in the gang war of Xanathar VS Zhentarim). There is a brief allusion to the Cassalanters in a Force Grey mission about the Black Viper, and there is also a mission to visit Jarlaxle in his ships at some point.
So, what are good guidelines to choosing the villain at the outset? Should it depend on what my players are expecting? Or on their alignments? Or just something fun for me to DM?
My thought process so far is to either go Xanathar or Manshoon, since those are the most familiar to PCs for most of the story. But even then, I only came to that conclusion after reading a few chapters, and I'm not sure if I should read the book in its entirety before starting the campaign.
If there are no official guidelines to this question, please back up your answers with your own experience.