What do you have now? It may help in determining overlap or diversifaction of your offerings.

All 3 will due the task for NA game with the proper bullet. Equally all three have ammo to select from and usually can be found quite easily as well. Little doubt the 06' will offer the lowest $ when buying, availablity and selection over the shelf ammo. The 7 rem mag has no short comings for ammo availablity, price and offerings, in fact it is probably the cheapest magnum ammo available over the counter. The 300 winnie has no shortage, availability should be pretty moot but the price will be the highest of the 3. Not that I think that should be your main concern, but it might play into your decision.

I use a 7rem mag personally for my all arounder it just boiled down to what I liked the best. I will tell you it was very close contest with the 300 winnie, so either of these 2 are excellent choices.