I was going to second pioneer.
Truth be told, 3/4 of speaker sound quality depends on what’s behind it. Speaker manufacturers “guess” at what might be behind it and tune their mechanics based on that assumption. I once heard that the standard is to assume a 1 cubic foot space behind it, sealed. If you were to actually to this and that were true, you’d get to hear what the mfr intended. Unfortunately, it might not sound great, because some really focus on showroom glam, with unrealistically sparkly highs and the like, which translates horribly to real world sound.
The best 6x9s I’ve heard were pioneer 2 way, paper cones, mounted in the kick plate below the back seat of a VW bus. Phenomenal sound, and as cheesy as the song was, Achy Breaky Heart hit the top 40 and it came out about as dialed in as one could hope for.
And I’ve spent over 30 years as a musician with speaker building experience, FOH (front of house) sound and other hobbyist endeavors. Car audio is stupid hard to get right.
