Your coices for us seemed to be 25-06 or 243.....or I would have suggested a 7 magnum also, since you don't have a magnum in your collection yet. I think everyone needs to have one!!! I personally don't think there is such a thing as "overkill", I'd rather have a little more gun than needed than not enough. But, thats just the way I am, not to say that a 25-06 or 243 would be better or worse.
Put it this way.....if I was sitting on a 200-300 yard shot with the possibility of something walking in behind me at 50, Id rather have the magnum. If I was sitting on a 50 yard shot with the possibility of seeing something on the far end of the field, Id still rather have the magnum, lol. I bring the gun that fits the longest shot I might have and still have lots of umph when it gets there.