Well if you look at my sig you know my personal preference, however there are a couple of hundred calibers out there that will work.
I live in the land of big wide open spaces, long shots can be had everywhere you turn and I like the .270 for its speed and flat trajectory. That being said a .30-30 is a lot better deer gun in some areas.
Personally I think that the whole fam-damily of .308 based cartridges are good deer killers. Anything based on the .30-06 is great too. I would say that these are the mainstream rounds, they are the easiest to come by and you really cant miss. Of course there are any number of slightly more obscure yet interesting and very capable rounds out there as well.
Magnums are not, never have been, and never will be necessary for killing deer, dont let anyone convince you otherwise. I have killed deer with a .243 and think it is a good round but I personally would not go any smaller, and in most cases the .30-06 is really more than you would need (so is a .270) but who has ever seen a deer that is too dead?
Six of one, half a dozen of the other, pick one that you like buy a nice rifle and some reloading gear, shoot it lots, get to know it, and go kill deer with it.