Rowing's good, IF it doesn't aggrevate the lower back or knees.
HIIT's as good or possibly even better than moderate longer cardio for fat burning, but everything i've seen says intervals & rests totalling about 15 minutes. Using a bike, which isn't quite as intense as some other forms of cardio, spinning/HIIT's basically essential, is not an option.
Swimming's the best all-round exercise AND is easy on the joints, but isn't considered quite as effective as others for fat-loss. Overall may be better though, when factoring in the reduced likelihood of stress on the body.