I say stick with whatever engine you are more comfortable with. If you know 4.6's..then stick with them. If you go to a 5.0 and don't know anything about them, you may make a costly mistake and it costs more to fix than if you stuck with the 4.6L to begin with.
I own two cars with a 5.0 and a 4.6L 4V. Which do i like better? Does it matter? There are pro's and cons with each motor. They both have the same amount of miles (94K on 5.0 and 87K on DOHC) and both engine run smooth and quiet. Which engine do i think will last longer? I have no idea. I don't hate either engine. I may know the 5.0 a little bit better though, so i would rather tend to build up a 5.0 motor rather than build a 4v motor only because i am more comfortable working on 5.0 engines. Doesn't mean i would do 4.6.
Stock for stock the 5.0 lacks the 4V's top end HP, but the 4.6L doesn't have the same grunt down low as the 5.0. Still, the 5.0 doesn't have that awesome feeling of pull and exotic engine noise at 6000RPM. They both get the same gas milage (i drive like an *** in both cars) and they both have their appeal.
Which do i like better? Not gonna say
