The corner will indeed give the most sheer output. Unfortunately, more times than not, it will also give the lumpiest bass response since it maximally excites all the room modes.
That said, it may still be the best PRACTICAL place. You can always do the crawl around method. Put the sub where your ears are (yes - up in the air too) and crawl around until you find the place that has the best bass (not necessarily the most). Once you find that, put the sub there.
It's crude and people will think you're nuts when you're doing it but it can work pretty well.
Bryan