Best shot (head shot) on the front and 3 on the back makes a nice Zed card. If you are going 8x10" (which is what I think of as a comp card) then face shot on the front and up to 5 shots on the back to cover your range.
I don't see a great vertical head shot for the front unless you go with one of your heavily made ones like this http://www.modelmayhem.com/portfolio/pic/31143043
. Eye catching but they don't show what you look like. Your other choice is very casual and could work but looks a bit lost to me http://www.modelmayhem.com/portfolio/pic/23523604
. Maybe this one http://www.modelmayhem.com/portfolio/pic/27940189
. Then on the back one of your full lenght shots along wit the heavily styled head shot from above and something more casual and playful. That would be my suggestions.