Nice question you have 
Well,alpine is great and very well HU.....But with imprint kit as mention by soundmaster,But Its price tag is thrice of the cost of your HU :P......So If you can afford it than buy it 
About Kenwood BT50u Hu than its a normal usb hu with bluetooth option,If it prove to be most essential in your audio setup than buy it 
About Kenwood KDC 7013U,than it is really great HU IF you find any 
It got DSP with DTA and built in Usb port.....which any other HU having DSP lacks.......
With the help of this Hu you do not have to face any phasing issue in sounding in your setup!
(So my recommendation is to get it,but again If you find any.....It is not available anywhere)
Rest,
Choice is yours .....