the gun you are most comfortable with, and have shot a LOT of loads through....the caliber is nearly irrelevant if the shot is placed perfectly...

for me, I have both a .280 (ruger) and a 300 Win mag (Tikka)....both are more than capable, and both are very good shooters...personally prefer my .280, as I have shot it more, and know the feel of it more...but my 300 is a tack driver on the range, even out to long distance shots

but I spend plenty of time on the bench and in the field, but generally find myself grabbing for the .280...

both are scoped with great glass, which IMHO is more important for the "distance shots" However, for me the longest I have shot a bull is 150 yards, always prefer to get close and see them, versus lobbing bullets from long ways away, so I rarely shoot those "distance shots"