I have both types... a 1995 P71 car and a 1987 police package vehicle with the 5.0L EFI engine. There are positives and negatives to both. I like the interior room of the older cars more, but the interior details are nice in the newer cars (by newer I mean up to 1997 or so.)
I liked the 5.0 EFI engine a ton better than the 4.6L. I have 234,000 miles on my 87 and 194,000 on my 95. Both engines have held up great, but the 87 gets the car down the road a lot better. Also, it's easier to find mod parts for a 5.0L than for a 4.6L.
But at the end of the day, I like the styling of the 95 better than that of the 87... but that's a personal preference thing.