Easiest?
Fi-Tech or Sniper - 7 wires, an inline fuel pump and a return line run to either the filler neck or a tank vent. No need for a new tank.
Best Experience overall?
Ford EFI
Easiest Ford EFI?
I'm going to go with Mustang on this one, the entire setup is stand alone and will drop on and run with zero modifications beyond the intake manifold and distributor. A tune is highly recommended - EFI Guy will be your resource for all Ford EFI swaps.
Most feature filled?
Hands down Explorer EFI. It seems to be the popular thing now, OBDII, trans control, EDIS ignition.
The obvious pro vs con is that the Fi-Tech or Sniper systems require the least work and RETAIN that original carb look. The Ford EFI have that large plenum intake style that makes them often difficult to fit under a hood.
I've run the 2bbl and 4bbl carb on a 302, swapped to speed density Ford EFI on a 5.0, then went 351W with Mustang EFI. After that ran well I had EFI Guy tune it and it ran the best out of any combos. I recement built a really aggressive motor for my trail truck and went Fi-Tech on that - runs 95% as good as the Ford EFI did. Zero regrets.