Neither. By the time you spent the money truing a 700 or Howa action, you will have spent as much, or less, on a true custom action. The Savage target action is a great option.

The Stiller Predator action is also a GREAT hunting rifle platform on a budget. I have had 3 stillers, 2 panda-style Vipers and a Predator, and all 3 have been fantastic. The nice part of a Predator is that it's a drop-in 700 replacement, so fitting triggers, stocks, and bedding blocks can be done by the shooter.

Moving forward, my long range hunting rigs will be built on Savage target actions, since I've had so much luck with my Savage factory rifles, and I LOVE the idea of swapping out my own barrels and bolt heads.