You need to say what it is you want to defend before you can have a useful answer. It certainly makes no sense to build even a single Golan II if all you're defending is a couple facilities. I would note too, that in general ships are a better investment for defense over stations for all the same reasons that tanks were a better investment than the Maginot Line. There are many reasons that stationary fortifications are sometimes not worth the trouble, and in a universe where we don't pay for travel expenses like fuel, those reasons are greatly amplified.
If you really want stationary fortifications, powerful shields and many weapons that can reach into orbit from the surface are probably more effective than stations. Distributing 20+ Planet Defenders across the surface is going to cost less than a Golan and be a much greater deterrent. Only the largest super-caps would go up against many Defenders at once. And finally, the best defense is likely to be in where you find your friends. Freelancers who don't have faction affiliations are going to be targeted by all factions as soon as EvE is enabled. There are going to be severe consequences for needing to do your own thing, and there is little anyone can do about this but join a faction.
My psychiatrist told me I was crazy and I said I want a second opinion. He said okay, you're ugly too.