Since most of my hunting falls in the 125yd or less range the 45-70 has seen all the deer hunting action from me for the past two years since I have gotten it. It all depends on your situation if you want a little more distance then go for the .35. I personally like to hunt up close.
When the .35 Whelen was developed, it was designed to take on Large American Game. The Winchester .375 H&H Mag was not in production and the long Mauser actions available from Germany were very expensive. The shorter ctg was just right for the 1903 action and the problem of an inexpensive Big Bear rifle was solved. The .35 Whelen is much more powerful that a .444 marlin and at longer ranges outclasses the .45-70.