I personally like the Fire Station right off the main street if you're looking for something in the town center, or head to the military barracks that is south of town

(Sorry, didn't see this discussion until today)
I would of course say it's my lake house on the Lake Ivy peninsula. The original map was just that house, the lake, and the fishing cabins. But there wasn't any loot or vehicles and it was way out in the middle of nowhere. So I basically made the town to support THAT HOUSE, and I haven't used a different place since. It's biggest drawback is there isn't much real estate on the peninsula itself. So if you want a large fleet of vehicles, you pretty much have to cut down a bunch of forest to have the room. Turning an Oshkosh around with a trailer is challenging.

My next top pick would probably be the shipping depot next to the highway patrol station just off the main Knox rd. It's fenced in pretty well. Comes with lots of storage, and relatively close water access. (Playing single player) I'll typically keep my home and storage at the lake house, and park all my large/extra vehicles at the shipping depot. Make it like an outpost.

I also tried to make all the farm houses fairly accommodating for settlement. A couple of them have a well, Barns and Space to expand.

Fences also run around almost the whole downtown. So with some creative barricading, I've heard some people like to block off the whole main st. area in the center of town.

Of course i picked the house. Love the map! But on that gameplay i ruined everything because of how much mods i had and how common good things was and when i got it all i was just bored with it all. Now im not playing much... of an anything.

I just got to the lake house and omg it is amazing. I won't have to do much decorating at all

there's a cool little cult like compound that's fully fences in on the west side of the town that may be a cool base location