RE: best caliber rifle for white tails???
Take your pick. There are so many combinations it will make your head spin.
For whitetails my favorite is the 6.5 X 55, but some are put off by it thinking it is hard to obtain ammo. It' s not that difficult, but it does cost a bit more than 30/06, 30/30 or .308
My second pick would be 7mm/08.
Hard to beat the 30/06 or .308 though b/c of the availability of ammo and different sizes and shapes of rifles chambered for both.