I haven't read any of the posts besides the first one. Excuse me if I step on any toes.
I have a "slightly" modified 5.0 Mustang and a 4.6 T-Bird. I prefer to drive the Bird for a daily car.
You are asking a bias group of people, so of course the opinion is going to be bias, and most that are bias have never driven a 4.6 to begin with.
For those who say 4.6's suck, they are wrong. A 98 GT on BFG's with just pulleys and Flowmaster 50's goes 14.2's all day long. I know because it's my Uncle's car.
For those who say the 4.6's are hard to work on, shouldn't be working on cars to begin with. They are no more difficult to work on, just a bit more involved.
For those who say "no replacement for displacement," or something to that affect that essentially says "the 5.0 is better," tell Bob Cosby that. He's got a DOHC 4.6 that is street legal, and NMRA F/S legal, and he goes 11.40's all day long, on radials. Show me a 5.0 that can do the same. Cripe, show me a H/C/I 5.0 in the 11.40's, because there sure isn't one that is F/S legal.
To the original poster: I'd go out and test drive each of them and decide for yourself. There is a seat for every ass.
Joe