Yeah the underhand is easier but the overhand does more for your shoulders and back, I think. When I was in a car accident back in college I had a lot of mid-back problems afterwards. What helped was doing wide-grip over-hand pull-ups where I'd put my head in front of the bar.
I need to get back in that habit, I could do about 10 with my hands a door's width apart.
Like this, with my head going "in front" of the bar. I didn't look like this though
