Which ages better: power, speed, fielding?

We keep hearing that a big home run, big strike out hitter like Chris Davis does not age well.  Compared to what?  A base stealer who no longer steals bases, like Jacoby Ellsbury?

Chris Davis

And what about hot shot fielders?  Jason Heyward supposedly has value because of his fielding, along with decent hitting with moderate power.  Heyward is the big impact non-pitcher among this year's free agents?  Really?

Davis is 6'3", 230.
Heyward is 6'5", 245.

Which one would you want at age 34?