Rogue comes to mind instantly.
Thinking a bit longer on it . . . hmmm . . . I believe the Barbarian is balanced, as probably is the 3.5e Ranger (but *not* the 3e Ranger).
Warlock is close to balanced, as is the Psychic Warrior and probably the Psion. The Wizard can be closed to balanced, depending on spell availability (ie: how many they manage to learn, which are available for learning, their spell selection, etc).
The Sorcerer I tend to ignore, having more or less replaced it with the Warlock, but in and of itself the Sorcerer is either a bit over or under balanced, depending on the campaign, spell selection, etc. I'm not really sure one way or the other about the Wilder, having never played one nor had one played in my campaigns.
Those are it amongst the classes I consider core (PHB, XPH, and adding in the Warlock as Sorcerer replacement). All others are at least a bit over powered (cleric, druid), a bit under powered (bard, fighter, soulknife) or have odd rules attached to them (paladin, monk - alignment restrictions on multiclassing, leveling, etc).