Depends what kinda cardio - I like Reebok DMX for running.
Ryka (made only for women) are the best I've ever had for step aerobics though! (Anyone else here do step aerobics?)
Oh, and FYI, anyone employed in fitness - coaches, trainers, aerobics instructors, can get a discount with Addidas, Nike, Reebok & Ryka (maybe others too). Good discounts.