There are a lots of 7MM's on the market today, so I'm gonna assume you are looking at the 7MM Rem. mag.
The 7MM RM has flatter trajectories and a little more ummph, it is a great long range caliber, and will take just about anything in North America, except maybe the largest bears!
As for the 30-06, what can be said that has not already been said?
It is the most used cartridge in America, if not the entire world!
I personally don't use the 30-06, I prefer smaller and larger calibers. However, if I was limited to one gun, it would probably be the '06!
You can't go wrong with either caliber so, good luck!