Everyone’s opinion is different, but I have done a lot of research, studying and asked a lot of questions of a lot of people about deer rifles before purchasing my newest addition to my gun collection. I ended up purchasing a Winchester Model 70 Black Shadow .270 caliber.
The 1st deer rifle I ever purchased was a Marlin 30-30. It was purchased when I was in college and is still a great gun that I still hunt with regularly. It has served me well over the years. If you are hunting mostly in thick woods and never over open fields, the 30-30 is an excellent choice. Another pro of the Marlin 30-30 is it is fairly inexpensive, lightweight and the ammo is cheap. If you are only hunting where you will get shots at less than 100 yards, it is a great rifle. However, if you will get a shot over 100 yards, you should look at stepping up to a flatter shooting caliber such as the .270. Although in the last several years, cartridge manufacturers have been making 30-30 cartridges that have a pointed polymer flex tip (Hornaday LEVERevolution) that shoots much flatter. This could bring the 30-30 back as one of the best deer rifles.
Why a .270 over a 30-06, .308, 7mm Mag or other calibers? First the .270 shoots flatter or at least as flat as any of the other calibers. Second the kick of a .270 is milder and therefore you are less likely to flinch when pulling the trigger. Flinching when shooting at a deer is usually not a problem as the adrenaline kicks in and keeping the shaking down is more of a problem than flinching. But flinching at the range when repeatedly shooting your rifle to get it sighted in is a problem. Also the milder kick is easier on your shoulder.
Another thought on selecting a caliber is the ease of finding ammo. The 30-06 is the most popular and therefore easier to find. I have know hunters who have forgotten their ammo and finding another hunter to share some of his ammo with you is easier if you have a common caliber like the 30-06. The .270 is probably one of the next most often used calibers.
Another reason for selecting the .270 is that if I ever get the chance (and can afford it!!) the caliber is large enough for mule deer or even elk.
Why a Winchester Model 70? Winchester invented the bolt action rifle and the other gun makers have not improved on it. The Remington Model 700, Browning A-Bolt, Ruger and others all make good guns. But the Winchester Model 70 beats the competition and is the best choice in my opinion. It may just barely beat out the competition, but I want that extra edge when I finally get that 8 pointer in my cross-hairs!