Unless you want to try a new farm type, you'll probably be able to see all the new content on your old save. I'd recommend an old save because most of the new content I've found so far wouldn't have been acessible right away if it were a new save.
Unless you want to try a new farm type, you'll probably be able to see all the new content on your old save. I'd recommend an old save because most of the new content I've found so far wouldn't have been acessible right away if it were a new save.