I have to say, I wish I had the kind of money you do, as for me I'd have to think long and hard before ever ordering one of these rifles as it would likely be a once or twice in a lifetime thing.
That said, I prefer a 30-06, but it's all a personal preference. I hunt with several guys that also like the 30-06, and several others that wouldn't have a 30-06, but love their .270's. Then there is one friend that has a .280, and wouldn't have any of the others. Then others that have to have the latest .300 Remington Ultra Mag, etc for deer, and that's what they want. It really isn't that one is so much better than the other as they all perform very similarly, it's just more or less which one you prefer.
That said, I'd have kept the .300 Win Mag if I already had it. While it is less overkill going with a 30-06 or similar, it's really not that huge of a difference. Certainly not something I'd have taken a big loss on a gun over just to change.