These are all good for both- .243,257 Roberts,25-06,257 Weatherby.Not a dog in the lot but the .243 leans a shade more towards the varmint side IMO than the others.The Weby is the fastest/flatest shooting of the bunch.The Roberts is a great old cartridge but not many makers offer that chambering these days.Really cant go wrong with any of these.Some mentioned the .270.While it will certainly get the job done it's really a bit overkill on varmints.