I don't think it matters much. I would go with non contoured myself for one reason, unless the pillar is cut to match the diameter of the action, and then lapped for 100% contact it will not be as true a fit as a bedded action.
With the non contoured pillar the bedding will be a little thicker and less likely to chip or flake off when removing the action than it would on a contoured pillar
This is just my $.02