Fluorocarbon for me. A local Bass fisherman put me on to fluorocarbon years ago. UB, I forget the advantages, but I like it.
I go from 4 lb. test early season then 2 lb. test though the summer.
Mountain stream, where the water is Gin clear and the Trout are finicky/spooky, I will tie on about four feet of invisible sewing machine thread for a leader.
With lighter line, make sure you have the drag adjusted right and don't lift Trout's head out of the water, beach 'em or net 'em.