The Daystar supposed to be full replacement poly body mounts which raise the body 1" over stock.
The JKS BL is a set of poly pucks which get mounted on top of the OE rubber mounts. So they need to be a) still there and b) in good condition as well.
Advantage here ... less vibrations get transferred to the body and you still have some flexibility instead of the more rigid Daystar poly mounts.
But both are good ... as are Aluminium Currie BL pucks and Aluminium Savvy BL pucks which get added to the OE rubber as well!
( and even some use non tapered poly pucks as well