Id go with the Pioneer, as to me have always been a better made product of hu within my experience.They seem to have lasted longer, and the functions are pretty straight forward, and easy to use.Just my experience with the brands overall,and opinion
I'm personally a fan of Kenwood's interface and prefer the 4V preouts. I also think that many Pioneer decks, including the 2300, looks ugly. But that's just me.
I'm not sure about double din's. But my Kenwood KDC-X995 vs my Pioneer DEH-P510UB was like vastly different. Kenwood's stereo has controls that really ****. Getting to presets ****. Changing stations ****. UI is just really bad. Pioneer on the other hand was simple and easy, and fast. Changing stations was a breeze.
Again, those were my experiences with single din's, dunno about doubles.