Attic ventilation is a science unique to the architecture of each building. There are no one size fits all solutions. I agree with the above posters, that ammount of ventilation is more important than type of ventilation. A common problem I see with alot of my competitors is that they like to spec ridge vent on EVERYTHING. Personally very few of the hip roofs that we shingle have long enough ridge lines for adequate ventilation via a ridge vent. Therefore we must spec something else on these projects.
I personally prefer ridge vent, but won't install it if I can't acheive enough Net Free Area, or if there is no intake. There are means of creating an intake but sometimes it's more cost effective to double up the mushroom/turtle vents to acheive the proper NFA. Having said that, all ventilation will work better with intake, some ventilation like ridge vent won't work at all without on intake.