Between those two, which has the most lowend?
The difference between the HC Boomer and the RC Boomer is fairly subtle.
That said, to my ears, RC seems to have a low end that's slightly more "open" than HC. The same punchy low-mids the Boomers are know for, but smoother mids with less of the raw grind. I like the way RCBs give a little extra body to my J bass tone.
By the way, the RCB set that went on my J back in September is still going strong.