RE: in your opinion, the best deer hunting caliber...
30.06, 308win/7.62X51, 30/30win; all calibers are readily available, your requirement dictates-brush, distance, bullet weight, etc., and they are all proven.
Availablity is a major concern when you look at some of the new whiz bangs. Ammo is priced affordably. In .06 and 308, you can use it for ground hogs to Elks; .06 if you got the cahones polar bear.
270win is probably another favorite; but imho it does not do what it meant to replace 243 or 30.06. Many folks will say its the greatest thing since canned beer; like anything else that compromises it is just that a compromise cartridge. It is no where near as versatile as an .06 or flat shooting as a .243.