Depends on power, enclosure, vehicle, charging, etc, etc.
There's a whole lot that goes into a system than the sub, why don't you list the other things like enclosure sizes, amp(s), electrical upgrades? Also what sort of results are you looking for? My mind goes to the gutter when you ask what pounds harder and louder.
ok 98 chevy silverado ext, i dont want a 18" cause i want multipule in future. i have 250amp alt, gona do big 3 when i get stuff, amp is gona be aq2200, and enclosure is gona be built to whatever specs for the sub or subs... there i hope that helps. i just want something loud and is gona shake the he!! out of my truck. my mind is set on the bl's but if i hear good things on a single fi btl then might change my mind