This basically boils down to weather this is going to be more of a fun gun or a hunting gun.
357 will be somewhat cheaper, and lots of fun, yet still fully capable of taking deer at reasonable ranges, if legal in your area.
30-30 will cost a bit more, still be lots of fun, and is definitely a deer capable round. Larger game too, at reasonable distances.
Chances are you will shoot a 357 a lot more than a 30-30. Best to get both?
When looking at rifles/cartridges like this its wise to forget about paper ballistics, ft/lbs, etc. If you solely go by that, you might be let to think that a 45-70 isn't capable of taking big game, that the bullet might actually bounce off, lol. If you wish to use a 357 for hunting deer, load a hard cast and push it as fast as you can. You will not likely recover one on a broadside deer inside 100 yards.