Depends on where you hunt. I spent last week hunting part of the time with an old Rem.742 in 30-06 and part of the time with a Marlin 336. I have killed a lot of deer with both. I like the 336's light weight and pointing characteristics for times when I'm hunting in areas where I may have to shift from one direction to another, i.e. areas where the deer could come from anywhere. I like the 742 in areas where I have a pretty good idea of where they are coming from and may have a longer shot.

In the end, either cartridge, 270 or 30-30, will kill the deer. It is a matter of personal preference. If you are going to potentially hunt in an area where you might have a shot over 200 yards, I would go with the 270. If you go with the 30-30, look at the Hornady Leverevolution ammo. It turned my 40 year old 336 into a nail driver and does a lot of damage.