I have had 12's in an 85 mustang and two 10s in a focus. Granted different enviroments, Buuutt, The 12s hit really low on bas but the two 10s Hit harder, I like infinity brand subs they tend to go deeper. Also look at other specs on a sub its lowest frequency it can produce, SPL the higher the better, Excursion is always is good thing to look at, My infinity Kappa Perfects have a 3" thick magnet on them.
Its all in sound prefrence. Box size and type out of the four common types play a big roll, I prefer sealed, Ported would be second bandpass last.