Flip a coin.

The 7mag is cooler.
The 30-06 is about the same without the kick and noise.

06 is cheaper to shoot.
7mag is funner to shoot.

At 500 yards you'll have to aim a foot or two over a deers back with anything. I think a 7mag dropps 36" and the 06 dropps 50" or so at 500 yards. Both have enough butt to kill a deer at that range.

I would go with the 06 and get a really good scope to put on it. Or buy that stuff in walmart that stopps glasses from fogging up. And then do alot of practicing.

"Hey ya'll, watch this"