Coilovers, unless....
...you already have a blower. The airbags are almost as expensive. Get power first. If you can afford the airbags, you probably already have the more important things like "STOPTECH" Brakes, and strut tower braces, Forged Internals, race axle, performance CAM/Intake. Yep. If you have all that...buy them (unless you are a "Low Rider.")