I have both a 1997 7.3L and a 2006 6.0L. Love them both. I drive the 6.0L - it is a great truck (son drives the 7.3L). Personally, I would recommend an 06 or an 07. Many have had good experiences with other year models, but getting one w/ warranty left is a huge advantage. If you do get a 6.0L, just read up on the proper maintenance things and it should put a smile on your face. When you see a truck you like, get an OASIS report on it. That will tell you its warranty repair history.

Oh yeah - the 6.0L runs circles around my 7.3L