what's the best 6x9 speakers

IF you want a good component set in back then look at Boston's RC420 4" set or their 4" FX4 coaxials ,and JL's TR400-CXi. For upfront on your dash I would look at Boston's FX7 or the plate version of it the 746. JL's TR400-CXi comes with 4 X 6 adaptor plates also. If you buy any of these coaxials or the component set then I wouldnt use an external amp unless its really small(25 watts RMS for the coaxials at most and around 35 watts RMS for the Boston component set).

http://www.bostonacoustics.com/ca_product.asp?Productid=162&CategoryID=14 

http://www.bostonacoustics.com/ca_product.asp?Productid=87&CategoryID=14

http://www.bostonacoustics.com/ca_product.asp?Productid=82&CategoryID=14

http://www.bostonacoustics.com/ca_product.asp?Productid=91&CategoryID=14

http://www.jlaudio.com/evolution/TR400CX.html