You've already recieved a deluge of useful information, so I'll keep this brief. I use a .243, but I know that it is a bit light for the bigger deer in the world. .270 and 30-06 are great rounds. 7mm-08 is great too. The great thing about .270 is that, wherever you might find yourself, you can buy .270 ammo. The nice thing about 30-06 has to be the versitility of it. I don't personally see any need for a magnum. If you ever forsee yourself hunting elk, nilgai, or caribou, go with the 30-06. Otherwise, you should like the .270 fine.