Which size subs hit the best?

It all depends on what type of music you are listening to. 10" subs will give quick high end punch where as 15" subs give a lower rumble type sound. 12" subs give the best all round performance however it also depends on the space available. Dance type music is more suited to smaller subs as they tend to have a faster beat which means the sub has to recover to it`s standard state quicker. aim higher 12" or 15" if you are going for more rap type sounds.

Any audio pro will argue between 12's and 10's. Tens are tighter and more accurate but can't get quite as low as the 12's. 15's are great to have as an accompaniment to a good 10 but by themselves, even a good 15 is sloppy and muddy. It's just not how they're meant to be used. They're great for very low bass and crap for everything else.

10's are great if you like rock and roll, because 10's are quicker and more responsive. 12's and 15's are okay if you are listening to rap. The biggest thing is buying speakers and an amp that go good together, with neither one overpowering the other.

i like the 12's better than 10's, u can feel em hit deeper in ur chest. and as for 15's u can really feel it, but they sound too deep for my taste

i personally like the 10s.... they are nice & arent too overwhelming. i have one, just one behind my passenger seat in my truck & it is nice & sounds great.