You can talk only in generalities when it comes to speakers.
So generally speaking, more expensive speakers are better than thier less expensive counterparts.
It might be best for you to choose a price that you would be willing to spend and then shop for only speakers in that price range.
Draw a line and accept something that is at or below the line.
You might also try to match power handling to the amp(s) that you may install in the future.
You might also accept some of the recs posted here since experience with any speaker is a better indicator than any $10k ad that might have been posted in Car and Driver.
Simplify your life and make your choice an easy one. Good luck

 

All I'm saying that as you move up the price curve for speakers, the differences become more and more subtle. Of course a speaker that can take more power and is smoother sounding will sound better but to me, at 75 MPH on the freeway a set of Infiities will sound just as good a a set of Diamond Hex's or Focals, etc. as long as you have some power behind them. I'd think adding some additional low end makes a bigger difference.

 

Alpine PDX amps are awesome. They run so much cleaner and more efficient, don't let anyone who doesn't have any first hand knowledge tell you otherwise. I have PDX 100.4 and 600.1. I had JL 300/4 and 500/1 and guess what? The Alpine set up sounds much better. I also am using a CDA9855.