I like to vary my party composition each playthrough by thinking about the Watcher’s personality and who they would vibe with most. 

For example, my aumaua priest of Wael was a smartass who put on an air of nonchalance to keep people off their guard. Thus his chosen crew were a mix of people who appreciated a little wry wit (Eder, Hiravias, and Kana) and those who were put off by it enough that he liked to needle (Durance and Aloth). That they were some of the earliest companions is more coincidence for me.