Personally I like flat (AKA Neutral) - in the middle hole - that gives you adjustment up or down - I have tried the deep down angle with canted shocks before in a 64B body full chassis car- it lasted one race and then we re-did the whole back end to a neutral position

If you have the room for a five hole front mount - go for it - in the end once you have it where it performs best - you probably will never change the front location again - just adjust with shocks.