First and foremost for me in Friendship I look at all the basic qualities that I can't find even in my family. As you must know some friends are worth more than family and the reason is because they're truthworthy, reliable, relentless ability to show concern in earnest situations, being able to be present in any predicaments.
Most important love. When love exists in a friendship, then other things will definitely follow because love is the most important virtue in friendship, when it's present it will be difficult to forsake someone you call a friend who is definitely in need.
For me the most important virtue is love.