Between these 2 calibers there is no question in my mind... put grandpa's old .30-30 back in the closet or take the firing pin out and mount in over the fireplace, but don't take it out in the woods, unless you have no other choice. The .30-06 is still one of the most widely used calibers, with most loads, slug configurations of any big game rifle ever. It is the father of literally 10-12 other calibers.
I think it was NRA's recent magazine that had a great article about all of this.
Certainly, there are other cartridges that are better for dangerous, longrange or very large game. But almost no others are as versatile as the .30-06. I would expect it to be around for at least another 100 years.