I'd say the Crossfire is a far more 'drivable' car on a daily basis. It's safer, more solid, quieter, and remarkably has more room inside than the Elise.

If you want to have a fast little car, get the Elise. The Crossfire is more refined and comfortable. The Elise is more fun, but only when you're tearing up a strip. The Crossfire would be more fun to just cruise in.