I would have to say Fort Mercer. Takes awhile to beat, especially since you will probably die to the gattling gun on your first try, but very fulfilling when you do.
I haven’t been to new austin but I do like shady belle so far . That is a good one indeed . You have a roof over your head , don’t have to go far to kill animals ( boars , gators and big fish around the corner and it’s close to Rhodes and saint denis . I like shady belle