Hertz or Audison? 5 1/4" or 6 1/2"?

[Tailgatepro]

Looking for either this 2 brands. budget $600 or below per pair.

Heard from friend said Hertz good in speaker and audison good in amp . True??

 

2) 5 1/4 or 6 1/2 which is better for mid bass ? saw some forum mention 6 1/2 much much better. true ???