when would you choose one over the other? This is for a swim jig rod, 1/4 - 1/2 oz, 7'2" MH Mod Fast rod. Will also be for pitching docks on clearer lakes. Watched an interesting video on fall rate for 20 and 10 lb floro, got me thinking...

Look at the line diameter. I bet there is not much difference between the 2.

I'm sure you'd be fine either way. My swim jig rods usually have 50 lb braid or 17 lb fluorocarbon. 

I rarely fish anything over 15. I keep 20 on one rod for bigger jigs, heavier cover type fishing.  The majority of my other rods including the one I throw smaller jigs and swim jigs on have 15. You're gonna get varieties of answers here so I guess its what you think you'll have more confidence in

51 minutes ago, Stephen B said:

I'm sure you'd be fine either way. My swim jig rods usually have 50 lb braid or 17 lb fluorocarbon. 

im thinking if I get into super heavy cover I have my other rods with braid, so floro is a good alternative

17 or 20 lb fluorocarbon for what?  I use 17 lb  for throwing 10" worm, because it casts the 10 worm and 5/16 weight a little better than 20.   (5/16 is where I generally start when 10" worm fishing  When I'm throwing my bubba drop shot rig I've got 20 lb on it because, why wouldn't you.  It is a little stronger and casting distance isn't ever an issue.

On my Biffle Bug rig, I use 20 because, I'm starting with 5/8 or 3/4 ounce weights and I'm bouncing them off deep rocks all the time.

Most of my pitching soft plastics to objects I use 15 lb Abrazx.

Was watching Mark Zona the other day and he was fishing a chatterbait on 20lb flouro.  I have used 15lb Invizx, but I may give this a try.

Of those two I would use whichever one I had handy.  Either way its heavy line!