If I am going to fish with Fluoro for punching, flipping, or pitching heavy weeds, I don't like using a leader for the simple fact that I don't want 2 knots that can potentially fail no matter how good you are at tying knots, or take your time. I use leader on braid all the time and like to put a long enough piece so it reaches the first guide on my rod, but when flipping, I go straight braid or straight fluorocarbon....Or Straight Big Game or Copoly.
I am convinced that in some weeds and structure, especially floating patches of cabbage and even pads with stalks will be more productive if you use a line other than braid....My reasoning and I first had this suggested to me by a friend I was fishing with, is that braid is loud when it rubs against the weeds,or stalks, and if windy, you can often hear braid from above the water and if you are flipping you are in close so fish hear everything..Braid is great for landing fish since it saws through weeds, but when lifting your bait it also rubs and makes noise...
I still use braid in many spots but braid also breaks often if you are not aware of a any fraying which can happen easy compared to a fluorocarbon, Mono, or copoly..
I use 20lb Fluorocarbon for most of my pitching and flipping if not punching since it has 17lb diameter, at least the Red Label, and I use 25lb for any heavy applications that require a heavy weight and a lob. I also use 20lb hybrid which has 32 pounds of breaking strength and only .01 diamater different than Hybrid line of 15lb test, and the 15 breaks at 22 I think...You truly can't tell the difference so the 20lb just makes more sense since it is almost impossible to break, and with the Fluoro coating and way they blend it it is stiff but great for flipping. just don't buy the ultra soft which is meant for spinning reels and is not as abrasion resistant..
To save money, I use braid as backing for Fluorocarbon since it is expensive and I only spool up 30-50 yards on top of the braid, so one pack of 200 yards lasts for 4 changes. If I was back in NY, I would only use 15lb test for most part, big game 15 is a great all around line, but just check diameter and remember, the thicker and the copolys as well as fluoro, will have more memory, but also if using fluro as a leader in cover, I would buy leader material which is more abrasive resistant if only putting like 5-8 feet of leader. I do that for my Medium action rod with 30lb braid, and use 17lb leader alot of times.
Keep this in mind...If you want you bait like a square bill to run shallow, then you can go heavy and use 20lb test, it may kill the action a bit, but if you are fishing a wake bait over grass and can't let you bait run deep, than heavier line can help...I like Fluoro for as much as I can use it...Braid frays easy and lines today are so much stronger than they used to be...I often pitch jigs into bushes and shorelines with 10-15lb test line for stealth and you would be amazed how well a good 10lb test line will hold up if you check it often, you also get more strikes with lighter line imo.....
Base line size on water clarity and always try to go lighter if you can, but if in nasty stuff, use what you have confidence in..I don't trust 2 knots for flipping or punching personally....50 yards gets you 4 changes on your flipping stick of 25lb test fluoro which rarely breaks....
I would suggest using 20lb Red Label Seaguar which has 17lb diameter, but for frogs people will tell you that you want a floating line like a Mono or copoly..You really can't go wrong with 20lb yo-zuri Hybrid, or CXX in 20lb...Just use line conditioner and break them in....Trilene Xt is easier to handle and at 20lbs is really strong...No wrong answer here, it all depends on the cover you are throwing too....I use a Swivel with a frog in lighter cover and just tie it to a leader, I just grab leader material which is Nylon or mono that Triple fish sells since it is inexpensive and awesome line made in Germany as an OEM.