Mark - Both the LSx and the 4 cam Ford v8s are dissapoint down low as standard (LS1 is better than the Ford but only just)
The commodore 4 speed autos like to blow up behind the v8s, so the BTR in the Ford is tougher for towing
The power steering pumps in the commodores are rubbish and WILL fail at some point.
The AU2 or AU3 Falcons with the last of the 302 Windsor V8s would be my pick, but they are f**k ugly, if you can live with that they are good cars and have good bottom end and mid range grunt.
What about a BA XR6 Turbo? Way more grunt than either the Chev or Ford V8s but sound shit house and may have to pay turbo tax on insurance.