New to car audio, looking for recommendations.

I am completely new to car audio. A friend of mine has subs in his car and about a month ago I ended up getting some subwoofers and an amp. I originally got a Boss Audio 1000w mono amp, along with 2 12 inch dual subs in a bandpass enclosure mainly because it was all cheap to start out with and I hated how the enclosure sounded. It overall had decent quality with low notes but wouldnt hit the highs right so I went out and got a 15" MTX Thunder 6000 in a ported box which sounded much better than the duals in the bandpass. I am now looking to get a new amp and subs and I need a few opinions from people more knowledgeable in the subject than I am. I am not sure If I want to get 2 12" subs in a sealed box because I feel the one 15" has too much trouble hitting multiple notes at once (such as punch notes on top of a constant low hit) and I thought a couple 12's would be able to hit multiple notes fine and have the best sound quality in a sealed box. Another option I was considering was getting a higher quality 15" subwoofer such as the fi Q 15 thinking it may have have better quality while hitting multiple notes but the problem with the latter is I heard that specific sub should be in a fairly large enclosure that I'm not sure if I could fit in the trunk of my 97 honda accord. So overall I would like opinions on multiple mid quality 12 inch subs VS one high quality 15"