What type of rack should I get?

The Sardo rack is a waste of money. It doesn't work on every table for one thing. You have to "train" the cloth for it to work. When you do that it makes a bunch of dimples in the rack area that can affect the path of a slow rolling ball. I'm not really familiar with the Chameleon, but you know it's really easy to rack a 7-ball rack with your bare hands and get it tight. I would probably lean towards the Delta rack (that's the metal one, I believe) only because it is less able to flex. To be honest, a good cheap wooden rack will serve you well for a long time. I will say, I love the wooden racks that come with the Diamond Pro tables.