I posted earlier about how to vent a bathroom fan thru a rooftop vent and was able to find an answer thru some ****** searches and a few phone calls.

My question now is, if the choice was a soffitt vent with the ducting laying horizontal or a rooftop vent with the venting being vertical, which method would you prefer and why? I live in Wisconsin so we have extreme temp. fluctuations. I am curious to hear from the experts!!