For distance, I've used 20lb mono in the past. For snag leaders I've used 45 lb quicksilver .This is also good in weed. For a general bullet proof , yet suttle and sinking leader of about 12ft , it's got to be 35 lb Seagaur Ace Hard . It's .47mm diameter I also use this for stiff booms. Give it a good stretch before you cast out.
For spodding and marker/ leading rods, I use The korda one , this is very robust and long lasting. Very reliable withstanding a lot of abuse.
Use the Mahin knot to join your leaders, it's easy to learn, very small and the tag ends face backwards as they exit through the rod rings. Hope I've been of some help.