If spinner bikes are like the ones used in spinning classes, I can tell you that they're more pricey. But, for me anyway, I get a much tougher workout. The bike allows you to be more "active" in your workout, by changing positions (sitting, standing, climbing, jumps, etc) and the resistance. There are also spinning videos out there for motivation. If you like spinning classes, then maybe a spinner is better for you. Try out each before you make the investment.
Sorry if this isn't what you meant!