The main line is 6lb Daiwa Sensor as it's tough and cheap. The leger link is lighter than the mainline, and preferably lighter than the hooklink too, the hooklink being Reflo Power Line in 0.15 for flake, paste and worm, lighter for maggots when I feel the need. Hook pattern and size being chosen to match the bait.
The snap link on the end of the leger link allows the cage feeder to be swapped to a maggot feeder or bomb as required. I carry a few of these links, with a loop on the other end, to make retackling easier in the dark after a feeder is lost to a snag.
All pretty self explanatory I think.