I've never heard that Magnaflow was bad, I had that system on my 1st gen Charger. It is expensive so you don't hear about many people having it. Borla and Corsa are in the same league, top price, top quality.
Flowmaster is a reasonable price, but they only use a cheaper stainless steel than the top price ones like Borla, Corsa, etc. With the way the Flowmaster mufflers work, don't expect a performance gain, just sound.
Something to consider is the Dynomax. Full 2.5" mandrel bent, aluminized(not stainless), turbo mufflers for mid $300 range. Another guy thought his was a bit loud and changed the turbos for Dynomax VT mufflers, still totally around $500.
Let me borrow your ears for a few days and then I'll tell you!!!
Seriously, what one person thinks is the best, the next guy will hate. In this case Utube is your friend... look for videos that show what it sounds like INSIDE the car while its being driven. Most videos show the back end of the car while somebody is revving it...great, now you know what it sounds like to people walking behind the car in a parking lot.
Personally, I don't give a $$$$ what it sounds like to others, what it sounds like while I'm driving it is my only concern.