Hello Fellow Fishermen!

I'm doing some sal****er fishing - and wanted to know if it's better
to use a swivel or a knot for the following line & leader:

15 pound Yo-Zuri Hybrid (Flurocarbon/Nylon) to a 40 pound Flurocarbon
Leader (100% Fluro: Berkley Vanish)

Swivel or Knot? If a knot is better, do which knot do you guys think
is best .. blood knot?

Thanks,

Jay