That's really hard to decide.
My Top 5 is this:
01.) To physically influence the elements
02.) To feel and manipulate the emotions of others
03.) To recognize relationships
04.) To shield me and those around me from special talents that affect the mind
05.) To show you what I'm thinking
Oh, i forgot the "why". Let's add: I don't want to torture someone. And to know what someones thinking? Would be an option, but isn't definitifley a favorit.