I love Regeneration
because it's spooky, it does a great homage to The Thing
, and it marks the first time Archer just straight up murders
people in order to protect his ship and crew -- a great foreshadowing of his actions in the Expanse. I think it's also clear that the Borg got the Bigfoot treatment between FC and ENT, and that between ENT and TNG, Starfleet gave it a big "well, whatever that was, it's gone now" shrug until they reappeared.