I have a A2 on my AR15 have been told that the 3 prong (Duckbill) does a better job than the A2 Birdcage for what they do. I am not concerned about Looks/or Period but Functionality of it. Which one does better ??
If you are not hiding from people actually shooting back at you just pick whatever looks best to you. There are some good comparison videos on YouTube.
I've always had the birdcage, never saw a reason to change them. There are so many, simple because they work. I heard the 3 prong ones sometimes make extra noise from the design, but I've never been around one. I personally think the 3 prong flash hiders are hideous.
One of my rifles (the only one threaded) is wearing a Levang Linear Compensator. The thing WORKS. It directs all the noise and flash directly out in front of the gun. Makes it quieter for the shooter and those nearby. It doesn't reduce recoil, but it makes it feel softer. It does reduce almost all of the muzzle rise. Unless you're going into combat and need the flash reduction, I'd much prefer it over any flash hider.