Good question, I was wondering that myself. I suppose if it is aged in the secondary you will have less sediment and a clearer beer since it will drop out over time before you bottle it. Not sure if there is a big difference though between 1 month secondary and 1 month bottle, as opposed to just two months in the bottle.
Since I have limited numbers of fermenters I usually go for bottle aging, though I will go with a secondary for big beers or if I got the time (and a lot of beer to be consumed)