There's many to choose from, but of those I've owned I would have to say my Rover SD1 V8.

It was a series II, manual 5sp, quad SU carbs, fast road cam. About 220hp and loads and loads and loads of torque. Built the engine myself. 4 into 2 into 1 tubular manifolds to a free flow exhaust.
Sports suspension (had to mount the pavement on one side to get into the Solihull LR plant!).

It was like driving Battlestar Galactica!! We used it to tow the rally car around loaded with spares. But when empty it was a flyer and a joy to drive. Beautifully sideways! And how it sounded!!

There's already a thread in Motoring on this.