Re: Darth Vader or Luke Skywalker?

Both are natural talents and the force is strong in both of them. But experiance should be considered - and Vader has tons of dogfighting experience from the clone wars. So I'd say during the battle of yavin I'd guess vader. However I don't think vader did many more dogfighting after Yavin and Luke propably had his share in the years that lead to Endor. So I'd also guess in the End Luke surpassed his father who also grew older - force or not.

Luke at the time of Endor or Anakin at the End of the Clone Wars - so when they were both in their prime?

I have no idea!