Thai Forest for me, mostly through convenience and proximity - the closest Dhamma center to where I live that also has children's programs, and has a path for taking the Precepts, is in the Thai Forest lineage (Portland Friends of Dhamma Center...fortunately they are also wonderful people from what I've seen so far!)
However, it's also by sensibility - I came to Buddhism from a decades-long agnosticism preceded by a childhood as a P.K. in Christian fundamentalism. So some of the more....esoteric, to be polite...concepts of most major religions have never resonated with me.
My study started with various Mahayana and Vajrayana styles, but I found them exhausting in terms of the high level of cultural/societal influence on the basic teachings. I'm highly respectful of them, but feel I need something more....foundational.
I tried the more vipassana-oriented insight meditation/Secular Buddhism approach, but it was TOO secular. I like my "rational" and "logical" with just a dash of "spiritual."