Should I go with Magnaflow F Body muffler single in double out. or
Borla universal single in double out?

Take your pic. There will be varying opinions but the real test is the ear. Try to find other cars with the same engine that have those mufflers and listen for yourself. Everyone'* ear is different.
My choice is Borla because I have one on my 4.L Jeep and it sounds great.
....but I'm sure it would sound different on my Bonne.

What are the cost differences? Borla is pricey but has a nice tone.

Some people here have sound clips of their mufflers. Hopefully they show up soon.