This is pretty much a subjective choice. In my personal opinion, you should listen to what sounds best to your ear and go with it. most car stereo places have the speakers in an equally crappy environment, but offer the ability to run off the same head unit and amps. You can get a general feel of the speaker in comparision to similar brands, but sound quality will change with the shape of your car and the mounting location.
I've done installs ranging from 1800+ watts with 4 15" RF Punch Pros (12 speakers total), to an economy upgraded speakers and an Infinity basslink sub.
My current install is 10 speaker, 900w in a cavalier. The speakers I chose are all Infinity Kappa. (didn't start out that way, but for the performance and price between them and competing speakers, I chose the Infinitys). Both Amplifiers are Autotek. My install was right around $1k, installed myself.
Hope this helps.