Alpine Type-R 12 - ****in loud for just 1 12, sounded not very good though but for the price id def take another anyday
rl-p12 - sounded great, punchy, got plenty loud for the price
SI Mag v1 12 - CRAZY CRAZY lows and sounded just as good as the rl-p, loud too
2 15" TC-9 based prototypes - for the short time I had them installed, they had decent SQ and decent output, great power handling, dont think I even gave them close to what they could handle
Sony Xplod 10"'s (the old red octagon shaped ones or w/e) - terrible
2 Alpine Type-R 15's - havent installed
MTX road thunder 12 - pretty shitty sounding, but got loud off 280 watts
Audiobahn Immortal 12 - decent, pretty good compared to other audiobahn subs but not something I woul dhave again
kicker s12l5 - decent SQ, pretty loud, one of my faves
2 kicker cvr-12s - sounded a little better than the type-r's and l5, got surprisingly loud and they were CHEAP
fi q 15 - sounded great and got low, but wasnt as loud as I expected it would be... the box wasnt exactly optimal though
fi btl 12 fully loaded - owned for like 2 weeks andd then changed to SQL/SQ over SPL, sounded decent for being PURE spl, got ****ing loud. i had 2k on it and it could have took a ton more
cvx 15 - never installed, I sold it, but looked and felt like a solid sub and i hear tons of good things about them
my faves are the type-rs, si mag v1, rl-p, btl, and the cvr for budget... the l5 was good too but I liked the others just a little more.
edit: forgot a couple old pioneer 10s I had, they were alright sounding but they got really loud, really surprised me the first time I turned the volume up. nothin to brag about SQ wise but they were like 50$ each so I was happy