Mrabyss

It is really gonna depend on the application. The speakers are going to sound different in different sized cars. Also are you going to be running the speakers off the head unit or through a separate amp? Personally I just got a set of Focal speakers that are the Polyglass series in my 370. When the tech demonstrated them they sounded better to me than the JL Audios. That said I love the JL Audios that I have running off a JL Audio 4 channel amp that are in my Tiburon. Both cars have Pioneer head units because They look clean and have all the bells and whistles without putting flashing lights and sirens on them. The other thing to take into consideration is type of music. Some are going to hit harder in the lower ranges and some will be crisper at the high ranges. Hard to get both and not pay an arm and a leg. So if your listening to the rap music go with something that performs in the lower range better and if its a lot softer of a music style go for a better higher range performer. The best advice I can give is find a shop that has many speakers you can experience and take a CD or Ipod and connect it up and see what sounds better to you. The other thing to consider is are you adding a subwoofer or anything? How loud do you listen to the music? Lastly fitment, not all 6.5" will fit the same, some have lower profiles than others. What kind of head unit and what kind of equalizer does it have or do you plan to use? Equalizers can do alot to help you boost the performance of the speakers since you can tweak things in different ranges if the head unit or separate device has those features(Pioneer does). This should all be taken into account.

apologies for the wall of text.