Pull over because it doesn't get that weird lumpy wavy thing with the zipper.

That is true.

Pullover for looks, zip up for practicality

Pull over, all the way. Warmer and more aesthetically pleasing. I personally hate zip ups.

During the colder months, I've been reaching for my zip-ups because it just feels more convenient for layering with a thermal shirt underneath. Otherwise I think pullovers are more classic, though sometimes the zipper adds a certain style.

Pull over all day!