Try Sunline Sniper FC 6lb and 7LB are my favorites to use on spinning reels, I don't like to use anything heavier than 8LB on Spinning, on bait-cast reels the heavier tests are fine. I use it for leader as well when using braid. Don't overfill reels and if you ever get twists in your line on Fluoro or mono let a bunch (more than your longest casts) out behind the boat with nothing attached troll it stretched out behind the boat for a bit then reel back in under good tension, this will eliminate a bunch of twists and it will perform much better. I will do this sometimes a couple times a trip. it makes a difference in the handling for sure. A good tug or two when you are on a snag or paying out some line and have someone hold the other end while you you give it a bit of a stretch will also help remove some memory in the Mono or Fluoro as well.
Often just casting jigs and grubs you will get a fair amount of twists from the lures spinning around during casts and of course reeling fish in when your drag is loose and spinning upon retrieve is a major culprit of line twist. I am amazed how often I see people reeling in fish and all they are doing is spinning the drag and not bringing the fish in. If you are reeling in fast and cranking like crazy and the fish isn't getting any closer, all you are doing is twisting your line. LOL
Mildog Out