Normally I would say the 25-06. However if you are going to keep your 243 then it would make sense to go with the 270 to seperate your options a little more. I condiser the 25-06 to be far superior to the 243 which I consider a good varmit rifle but not really a deer rifle. The 270 though would be a good choice if you are keeping your 243 for the smaller stuff.