Easy answer......
What ever is on the other end of my key!!
There is no "right answer", it boils down to what you want, what sounds the "best" to you, and your own mechanical skills.
When I ordered my car 5 years ago, for me that was the 460 and still is! The 351 strokers were just coming out and did not have any history but times have sure changed!
My suggestion is beg, borrow, ride or drive in as many different combinations as you can and pick the one that best pushes your button. That will be the "best" one for you, and that is really all that matters anyway!
Good hunting........
John Russell
SPF#586