I think you might be referring to my thread about the 2 12s or 1 15 in my Sonoma? I think I am going with 1 15 for a few reasons...
Sub can have more airspace sine only 1 sub and im limited on room.
Cheaper.
Looks better.
Blows people away when they only see 1 sub.
And the box is a TAD easier to build but not much. So I am doin around 3.5 cubes tuned to 34hz. Hopefully on an Orion 1200D or so. Should get a little loud.