Meh... that's not balance, lol.
Oddly enough, the most balanced lists are the ones that will struggle most against most recent codices/army books. Most lists, even the most balanced, can still be tweaked into a WAAC army with little trouble, but the armies I see as the most capable while remaining the most balance-friendly are these:
Orcs & Gobbos
These armies still remain true to the 'core' of the Warhammer Fantasy concepts. They do not change basic rules to fit their 'new' style of play. These armies can be quite competitive without the use of uber-characters or masses off Rare/Special choices.