My favorite deer rifle is whichever one I happen to be using at the time. I hunt with a 243, 6.5 Grendel, 6.5 Creedmoor, 308 mostly. I bought a 30-06 and may use it some this year. Also have hunted with a 270, 7X57, 35 Rem, 44 Mag, 6.8 SPC, and 44 Mag.
If, for some reason, you put a gun to my head and told me that I had to go kill a deer today, or else, I would probably drag my Model 700 Classic 270 out of the safe, and use it with the utmost of confidence. I've killed a slew of deer with it, and the only reason I don't hunt with it now is because I just like shooting different rifles.