Would respectfully suggest the 3.0 V6 is the very best, slightly higher compression, and the most torquey of the bunch.
Please read my "mile muncher" thread.............
The 3.0 is possibly the most frugal on fuel too if you don't have a lead right foot. on a good run, 30mpg is EASILY achieveable, although more like 23-26 around town.
Speed wise, in my opinion, the 3.0 is the best too, several of us on here have seen 150mph (and more!) There are some better points on the 3.2, i.e. DBW and better exhaust manifolds, etc. but in essence, the 3.0 can be made superior in all respects easily and relatively cheaply. Oh, and the 3.0 doesn't suffer from the 0430 code from the lambda sensors either!!
Just my (slightly biased) opinion.