Haha, I hear you man. I just can not make up my mind on which to run. My mind changes every day.
AQ's = More budget friendly, but will they play clean/low enough for my application
will play clean, and assuming you tune low they will play low. i dont really give a shit what anyone says about tuning to 40hz, at least not for my application. works for some, didnt work for my vehicle (explorer)
BTL's = Low end monsters, whom I've heard, but not very easy on the wallet
low end is right, definitely not easy on the wallet though. the plus part about it: its natural tendancy to play super low, and lots of motor strength (the new one available may first will have a larger gap and still be more powerful than the spl version of the old btl) allows you to use smaller boxes and tune higher to add a little peak up top. at least for me, since mine lacked upper end response in 4.5 cubes @ 33hz. i think 3.8 cubes at 35hz or so should add a little to it while not sacrificing too much down low
BL's = Easier on the wallet, but will they get loud enough for my application
with the right power, i think they will do just fine. i will say this though, in 6 cubes, the 18's dont get very low. i think they need a much bigger box. however the Iron Law, says they might just need more power for low freq extension...
It never ends //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif