The LFA may sound great, but given the choice, no question, I would get the Ferrari 458. The 458 has 18 more horsepower, 44 lbs/ft more torque from a 4.5L V8 vs the 4.8L V10 in the LFA. Plus the 458 is 200 pounds lighter. The 458 should eat the LFA alive on the track and in a straight line.
It's not like the Ferrari sounds bad either.
IMO, a car should be judged on its merits, not on how many are going to be produced. The limited production of the LFA may make it more expensive than the Ferrari, but IMO, doesn't make it any more desirable.