To have the best response in a room across all seating locations, you need multiple subs on opposite centered walls. The subs output is omnidirectional, so firing the woofer towards the corner does nothing. One sub can do a good job if placed correctly, so find the location that gives you the best overall performance in the primary seat. This could be anywhere in the room.
Placing the sub near one of your corners will excite all the nodes and give you better boomy sound, however, this is not always the best placement for the best FR.
