Noel,
That is an almost impossible question for anyone to answer. Basically it comes down to you and what you want in the car. All replicas today are for the most part very well made and not the glued together kits of years past.
How accurate to the original are you wanting to be? Do you care if it looks exactly like an original? The Big Block/Small Block can be argued until dooms day with no winner. They both have their advantages. A 427 side oiler has an
oil gallery on the side for the lower end and screw in freeze plugs. Many of the earlier 427s were called center oilers because that was the way they oiled. But when driven in race conditions, not enough
oil got down to the bottom end, hence the side oiled was developed.
As to which is the best car, almost every person has a different opinion. Superformance is very good I think, and ERA is about the top of the line except for The Shelby's and Kirkhams. If you order a Shelby, you won't have the stress of having to hurry to get everything together. Right Jdog!
Ron