A bit of a mix in my case. I've only just finished Mei Fengs crew, but plan on expanding with Kaeris and Misaki, which means a lot of interchangable models. So for me it is a mix of finding masters I like and then picking the ones that still hold models usable for my other masters. I think Ten Thunders is good in that regard, since they have quite a few dual faction masters that can encourage delving into other factions. For instance Yan Lo also has my fancy, and will probably result in me taking a look at some of the other ressurectionists.