Wich axel is the best for me?
The big difference is that one is fabricated and the other is stock looking. If your building a car to be stock and show like then the factory looking one is what you want. if you don't care what it looks like then I personally like the fabricated housing. its built a little more stout than the original housing.
as far as what type of axle you want, IMO I think you'll be happy with a 8.75" Mopar axle. Its strong enough to handle your power range and lighter than most other axles. Plus the 8.75 was meant to be in a mopar so its easier to have it adapted to your application.