This.
Don't let yourself get fooled by the name of the class; 4e is not 3.5. You're best off forgetting everything you ever learned about 3.5, because often you'll find that your 3.5 experience will mislead you when playing 4e.
Pick a role, and a style of play. (by this I mean, do you want to be a front-line combat leader, a sinister shadowy arcane killer, a shapeshifting defender of nature?) These ideas will inform which class best fits.