I have used Kicker, Infiniti, Orion, Pioneer, Kenwood, Alpine, Rockford Fosgate, Altec-Lansing, JBL, Cerwin-Vega!, and even Boston Acoustics over the years. I never did own MB Quart, but I knew a few guys who did and they sounded awesome. Pioneer, Alpine, Rockford Fosgate, and Kenwood all have really crappy entry level speakers, but also sell more expensive higher end speakers. Right now I have Pioneer 4-way 6.5's in my truck. Zero bass response but awesome mids and highs. But I also have a Kicker 8 inch sub that I got from Tobias, so that makes up for them not having any bass output. Hands down the best sounding speakers I ever owned were a set of Altec 6x9's, and the best subwoofers I ever had were some 10" Cerwin Vegas.