@Warlocke,

The next line in the PHB after your quote reads:

"Your choice might correspond to a particular sect dedicated to your deity. Apollo, for example, could be worshiped in one region as Phoebus (“radiant”) Apollo, emphasizing his influence over the Light domain, and in a different place as Apollo Acesius (“healing”), emphasizing his association with the Life domain. Alternatively, your choice of domain could simply be a matter of personal preference, the aspect of the deity that appeals to you most."

I believe that this explicitly states that your choice is a matter of personal preference.

Additionally, the 8.2 AL Player's Guide states:

"Deities. You character may worship any deity listed in Deities of the Forgotten Realms and Nonhuman Deities table in the Player’s Handbook or any of the deities mentioned in the resources in Step 1& 2, above. Clerics must worship a specific deity but aren’t limited to the Domains recommended for their deity."

<3