Colder temperatures slow the aging process, while beer ages faster at room temperature. That's why beer (and wine) is stored cool for long term storage.
If the beer needs some time to age out, aging it at room temperature would be quickest.
Cold conditioning has it's place as well, as some beers really take on a "crisp" note as well as clear in a cold place.
It would depend on the reason that the beer needs aging. If it's a big roasty stout that needs some time for the flavors to meld, or something that is oaked, and so on, with complex flavors that need time to age out, room temperature is best.
if the beer is hazy and not clear and not quite crisp enough, but tastes "done", then cold conditioning would be a viable way to achieve that.
If someone is aging a beer because the instructions said to, it would still depend on the brewer's goal for the beer. If the beer tastes perfect the way it is, the ideal storage temperature would be fridge temperature to preserve it at its peak.