From a capability standpoint, 4th and 5th gens are nearly identical frame, suspension and drivetrain. There is no clear "best" unless you have some specific need.
For towing or if you just like more power, a 4th gen with the 4.7 would be ideal. Post 2005 4.7 has vvti, which is good for a few more ponies and a 5 speed transmission compared to the 4 speed found in 2003-2004. Downside of the V8 is it has a timing belt instead of chain, and it can't be upgraded for power like the 4.0 can.
Other than that, pick your poison in terms of packages, options, looks, etc. I personally think the pre-facelift 5th gen 2010-2013 is beyond fugly, but the 2014 and newer ones look OK.