My three mafia families are at the top, but if I don't count them, the Galloways.
... Which is pretty cool considering they started off as one of the poorest families around... 6 kids being raised by a deadbeat dad and a kleptomaniac mom. (Well, she would've been a true kleptomaniac if it existed in 4, but pickpocketing works, I guess.)
One of the families I rotate with. Eventually with them all at the top of their careers (except for one lazy one LOL) they racked up about a million or so via investing and working only. Currently half of them are now dead, and the last 4 are elders. They have like 4 kids to carry on their name though.