I'm running one Alpine Type-R 12 off and MTX Thunder801d mono amp(775w trueRMS). and it sounds freakin awesome, you would never think it was only one 12. I listen to ALL kinds of music and it's super clear and super accurate, not to mention it can drop some low notes.
I'm probobly going to go to 2 MTX 8000 12's, but thats just because I want to kill people with my bass and the amp I have isn't getting used to it's full potential off the one alpine. (but the damn dual voice coils make it so I can't just drop another alpine in)
I also work car audio at Circuit city and I listen to all different brands all day. - In general with car audio you get what you pay for. A 1000w amp would never be only $199 - stupid sony garbage.
we just started carrying Audiobahn too and I think their stuff is good, but not the best, but it is better than alot of other stuff.
15's weigh too much, the boxes weigh too much, take up too much space and are slow as hell, if you listen to any sort of rock music don't do a 15.
fosgate - is cool, but their low end is garbage.
Sony - is garbage
Pioneer - Great decks, not so great subs and amps. premier stuff is pretty nice though
Kenwood - a little better than sony, more power and a little cleaner, but again $199 for 800-1000watts, yeah right.
Alpine - is nice, but I think their amps are kinda weak for the price, but they are some of the cleanest amps I have ever used. Their subs are awesome too.
Bazooka is pretty decent esp. for its price, good dollar to watt ratio. I acctually like their amps - wouldn't buy them for myself, but good if your on a budget.
Audiobahn - good power, realistic in price to watts, a little more show than go, clearer stuff out there.
MTX - I love MTX. True power and lots of it. very clean sound realistic pricing. Their new 9500 series subs are going to be insane! 4 full inches of excursion! 750-1000w true rms handling! Expensive, but you get what you pay for ($399 for 10" $499 for 12")
Lightning - Low end fosgate, but the strike series is pretty good, their demo Jetta lives around here and it sounds sweet.
there are so many more brands, but I would probobly suggest checking out smaller companys that are building up. MA audio is AWESOME(not mobile authority) MA. Visonik is nice, Memphis, MMats, diamond.
Stay away from - profile, PYLE, Lanzar.
sorry this post was so long. Just trying to help.