Not a fan of the FMF Apex exhausts, but this does not mean that they arent any good, just my individual tastes. Looks too MX for me.
Mate all of the aftermarket exhausts sound very similar in tone, some are louder than others though, noteably the 2Bros and the M4. My advice would be to purchase what you think looks best for your bike. I would hate to end up with an exhaust on my bike that looks shit, just because it sounds good.
You will find that if you like the look of the exhaust, you will most likely enjoy the sound. And any exhaust will be 100% compared to stock.