Facebook for business: Fan page, regular page, or domain name – which one is best?

For a business, which scenario is the best use of Facebook:
1. Fan page – maybe I’m missing something, but the wall function doesn’t carry over to other users.
2. Regular page – this works just like a personal page with a wall
3. Domain name – in other words, just have a Facebook Like button on the company site that points to the company’s domain (example.com)