So i just got 1994 Buick regal grand sport coupe do y'all think one badass 15 would sound better than 2 decent 12s?

 

2 badass 12's will be louder all things being equal, both will sound great if set up right. I'd see how much space is needed by the subs, and what you're willing to give up. Then match sub to enclosure and give it enough power..can't go wrong either way. I've had great sounding 15's, 12's, 10's, 8's...even 6.5's in an 8 speaker array. The key is to not go cheap on the required volume...especially with 15's...they need a lot of space generally to function as they should. The Alpine type R 15 in a 2.75 cube tuned to 32 hz worked very well for me in a Chrysler 300M driven with 1000 watts rms. I swapped it with a DD 2515, but it didn't sound as good...the DD needs around 3.5-4 cubes...it was loud though. 2 type R 12's in 3 cubes tuned to 35 hz with 1000 watts rms really pounded and sounded great with everything from classical to reggae. It was definitely louder than the 15. Both sounded great...I would do either again if I had the space.

 

I agree with veeman, my vote is for the 2 - 12's.