Neither is better or worse than the other. As long as the boat is designed as an offshore boat then either will work fine. Deck stepped masts have no big holes in the deck.. good thing and if the
rig goes down odds of whipping around the interior is 0 also a good thing. Bad thing is keel stepped will more often give you a larger stub to work with.. Also on decked stepped the compression post/bulkhead is a critical piece of gear while on a keel step this does not exist.. just different engineering.
FWIW the Moody is deck stepped and clearly an offshore boat, most HRs are decked stepped as I recall.. I know my friends new 40 is.