I want to know what the best leader brand and pound test for clear water with visibility up to 3-4 feet, but we have 6-7 pounder bite so it has to handle big fish

I use invisx

I use fluorocarbon leader material for leaders.  Much stronger, and abrasion resistant that any reel fill line.  I prefer Seaguar.

This is a question I have had for a while.   So specific leader line material is a much better choice for leaders?   Good knots?, flexible for a natural presentation?     I will gladly buy this if it is better.    Thanks

I use Seaguar floro. The fish don't seem to complain.

I use p-line cxx 17lb for leaders. I fish it hard! I was fishing heavy cover this weekend, pitching to the dead center of it and wrenched 2 fish over 6lbs out of it. Not saying another line couldn't have done this but for a line that's 10 bucks for 300 yards, it does awesome. 

I know this is the wrong answer, but I use either Big Game 15# fluorescent white (clear) or Trilene 10# XL lo-vis green for the finesse situations. I have used fluoro but just haven't bought any and I have a lot of these 2 monos left. You just have to check and retie sometimes.

Blue label is my first choice, but if I don't have the specific test, I will substitute some main line remnants 

Leader material is actually stiffer and tougher than normal mono or FC designed to be line as opposed to leader.  No problem with knots if done right (as with any line/leader), the stiffness is not an issue on leaders, and can actually be an advantage as it keeps lures that are aggressively jigged, like blade baits, from fouling as often.  I try to use it, but when it gets lost, I just use whatever FC line I can find.  IMHO, FC leader material is better than FC designed to be line.