depends on what you are trying to achieve, SQ,SQL(daily driver-Loud), or SPL? there is also not one # 1 kill all sub and amp combo there are a few that stand out above the rest all the time.
well to name a few brands to look into for subs Image dynamics,RE audio,Sound splinter,Crystal,JL audio,Treo,Digital design, those are a few of the brands that are highly reccomended. For amps JL audio, Arc audio, Zapco, Sinfoni, Brax, old PPI art series, old Orion SX and HCCA model's, old RF power and first edition punch(80's and early 90's) those are a few there are more in both catagories but you can't go wrong with those.
well u might want to figure out your budget but i would say a dd 9910 with a orion 2500d and then a 300 amp ho alt and some 0 gauge running it then u need some comp speaks
don't waste the money on a type x, listen to the suggestions above. if i had that budget i'd either get a dd, crystal, treo, re, or aa, probably in that order.
just make sure you build your own box to save some money and al the brands that ctmike posted look into them i would say dd, treo, re or aa but ya dont get the alpine type x for yuor first sub its a watse of money