Limber: yes. Best hitter I ever saw in person: Ted Williams ("The Splendid Splinter"). Hit home runs in old Griffith Stadium, and that was a feat.
Best I saw on TV: Hank Aaron. Story our Frank Howard tells about a discussion at an All-Star game:
Hondo: "Hamerin' Hank, can I see that bat you use?"
Aaron: "Sure, Hondo. I admire the power you've got"
Howard says that Aaron's bat had one mark, about the size of a quarter, square in the center of the barrel. "My bat had dirt marks all over the place. That's why Hank Aaron hit more home runs than anyone and why he's in the Hall of Fame. Aaron hit everything perfectly".
I loved watching, and hearing, Frank Howard smash a line-drive into the upper deck at DC Stadium, but if the new-model limber Bryce Harper hits .325 with 40 or more home runs, then he will have become the sort of hitter baseball has rarely seen since Frank Robinson.