--IMO, all of them.
Absolutely correct. Those who see only haredim or datim as Jewish are taking a very narrow view. Lets put it this way: on Rosh Hashanah 86% of Israeli Jews were at services. That obviously includes the vast majority of the 70% who are labeled as chilonim.
Observance of mitzvot are important, but they are the result of being AUTHENTICALLY Jewish. There's an old yiddish expression which, roughly translated, states, "first of all, be a human being." The yiddish word for human being is "mensch" with all its connotations of substance over form. When an Arab murders four young girls and then shoots their pregnant mother in the belly, the AUTHENTIC Jews cries out in pain, and demands justice. Those who are merely born to Jewish parents react by giving up land to murderers.
It reminds me of the Curb Your Enthisiasm episode where the guy accuses Larry of not being a real jew because he was humming Wagner and Larry offers to take it out to prove his jewishness.