My favorite is Leo Manzano. Has been for years.
I've been following him closely since he came out of college.
Partially because he was coached by my old coach and because he is fun to watch and he is gracious.
I have met him in person a couple of times and have just found him to be very likable.
And he seems to be constantly the underdog.
In the 2012 Olympic final I watched him closely, which was hard because he was far back most of the race.
To see him reeling people in over that last 200 was exciting.
To see that he was the one to break the 44 year drought of American medals in the Olympic 1500 was very satisfying.
Seeing him overcome his sponsor issues and win USATF this year and run 3:30 was also gratifying.
It's just cool to follow someone for a number of years, feeling their ups and downs, and enjoying their success.
To me, he is the ultimate over-achiever.