[daepp]

Here's a bit from my experience. I have had about 60 F-150's and F-250's over the last dozen years (contractor).

2004 to 2009 - get the 5.4. The 4.6 was anemic then and the trannies prone to failure. Also, regardless of engine size, the front rotors have made-in bearings that are prone to failure. Not much to do but replace - fortunately they are not that spendy. These trucks have a great ride!

2010 (maybe 2009) - 4.5 is a 3 valve - much smoother, better power, better tranny.

2003 and earlier - completely different truck. Engines are solid, most common problem we've had is an occasional bad coil pack. They do not have near the ride of the 2004 and later trucks.

Hope that helps.