Depends on which style of play you prefer ofc...
Burst Assassin: Go Nocturne
Assassin Off-tank: Go Irelia
Dps/Burst Mage (with a learning curve): Go Cassiopeia
© 2013 Riot Games, Inc. All rights reserved. Riot Games, League of Legends and PvP.net are trademarks, services marks, or registered trademarks of Riot Games, Inc.