Both are equally good options.
The goal of cardio is to simply burn calories. It does not matter what form of cardio you do, as long as it gets you moving and gets your heart rate up!
The bike, treadmill, step mill, rower, bur-pies, skipping etc. are all equally good options. If you don't like doing traditional cardio on a piece of cardio equipment, then things like MMA classes, swimming, playing floor hockey or basketball etc. are great options.
At the end of the day, anything that gets you moving and increases your heart rate is a great option and good for fat loss!
I actually recommend swimming to a lot of my larger clients for cardio because it is very non-invasive and causes no joint pain.