I -personally- don't like lower half doors only. (we sell them, so this view may not be shared by management!
Lowers are great around town, and fantastic on a trail. They are less fun on the freeway on your way up to the trail. Especially here in Colorado, where it can be 80 degrees in Boulder, and 35 up in the mountains.
So I like doors with uppers that I can take off and stow in the back.
(we sell those too! - I'm adding this in case my boss reads that first line).