If I had to choose one of these I suppose it'd be the .270 because it gives me more options in the future. But, I love carrying my 336. The last two seasons I haven't even touched my .30-06 because I like carrying the .30-30 so much. The .270 will give you a little more range probably. And be a better option for some future hunts. But for just hunting whitetails and normal ranges the Marlin is hard to beat. Mine will also shoot 1" groups at 100 yards which I was very impressed with. I had always heard that levers weren't as accurate as bolt action rifles. And that may be true, but a 1" group at 100 yards is nothing to complain about.
-Jake