If "beginner" means a player with enough knowledge (on item building and other stuffs), i would recommend INVOKER and GRAND MAGUS.. i was just joking!
Try these:
1. Lion, Rylai, Sven, ES, VS et al: Stun, slows, and disables come in handy. Good for ganks and escape.

2. Slark, Davion, Omniknight: Built in heal and regen

3. Axe, Centaur: High HP

4. Ursa: More life = More damage, survivability = ownage

5. Jah'rakal, Mortred, darkterrror, Traxex, Spectre, et al: Good killers though farming is vital.



Avoid invoker, magus, potm, techies, pudge...