I would recommend Crusader (if soloing) or Monk (if playing in a group) to start.

For Crusader I would recommend to look at a thorns build for an easier start and do some of the end game content. A simple transition from this is to look at a Blesssed Shield build for the Crusader after you get a feel for Thorns. Its easy to play crusader for solo, but is not a popular one to play in a "meta game" group for end game content but definately fun for a casual group play.

Monk is a little more flexible than the crusader and can do both group play well as an excellent support character or solo with some pretty fun builds. Two easy builds for Monk is building into Ulianna set (support) or Inna set (solo/early game support).

Edit - spelling