Either would be a good rifle. To me, it is a matter of preference, unless you are going to be doing your shooting past 250 yards or so, then the 35 Whelen would get the nod. of course, unless you are going to be shooting big bears out that far, the 30-06 that you already have should handle it. On second thought, buy both.
I personally bought a 444 over a 45-70 because I could care less about what the horse solders carried (this IS the 21st Century). If I want to remember anything like that I will just watch an old Army - Indian movie, then I remember how crude and fragile fire arms were. If I am going to shoot a modern, rifle I want to shoot a modern case. If I want to shoot an old case like a 45-70 or a 45 Colt, then I will shoot a trap door Springfield or an 1873 SSA colt or replicas. But that is me, and I am in the minority here.
I already loaded for the 44 Mag so bullets were readily available to me and I did not have to stock yet another size. Plus the 444 had a good reputation for accuracy and it will put down anything that walks, crawls or flies in North/South America. If I would go to Africa, cough never, I would be taking some thing besides a single shot 35 Whelen, 444 or a 45-70 for big stuff and for the smaller stuff a 30-06 would do the trick.
Good Luck and Good Shooting
