Is SC or GA more car hobby friendly?

Yes, you can run year of manufacture tag in GA.
Or get "antique" plates with cute Model A whatever or other on them.
(Not my cup of tea)
But you gotta pay something every year.

One thing I know for sure.
If you don't have a "title", Georgia will not issue you one.
Old cars are not required to be titled here.
So, you should not have to pay a title transfer fee unless you have PA titles and want to get a GA title.
You will be issued a registration no problem though based on your PA registration.

Now that new advalorem tax thing I'm not sure about.
I THINK you may be grandfathered in.
I say that only because I asked at my county courthouse when I was getting all my tags last year about transferring an antique car to another person.
I was told that it would be "grandfathered" in.
I took that to mean the next person would only have to pay the yearly ad valorem on an antique car.
Which is something like 22 dollars on my antique cars.
That big one time tax is for selling newer cars with a known value......I think.
Could be wrong.
On an antique car of unknown condition, they take your word for the value as far as I know.
All your cars are worth no more than about 1900 dollars aren't they?