the sub is just 1/3 of the setup, proper box build and design, and power and tuning, all together will make or break a system. With over 20+ years of install, i have used/seen it all, the constant from their beginning as been JL - you could not go wrong with them, MTX is not what it used to be (I was once sponced by them) but i am sure they still have some nice products, Kicker I always hated - they are a 6 month sub then they sound worn out.....
the Fi & Re lines seam to be a spl sub - but i would put a 13w6 against them anyday. Any shop with the great big phone book like catalog of parts can order them along with pyle, lanzar, us amps and several other name brands that have gone to the mass distributers, You get what you pay for and that goes with product and labor, in todays market it really is a buyers market and you could almost name your price.